Xcode 12.0 and ToolChain Error

I updated my Xcode two days ago. After the update, I got a warning error about ToolChain failure: 

/Library/Developer/Toolchains/swift-2.2-SNAPSHOT-2015-12-10-a.xctoolchain:1:1: failed to load toolchain: 'Version' parse error: Could not parse version component from: 'swift-2'

There is no further explanation about this error in Xcode. After Google search, I found one solution. It seems that it is caused by Xcode missing remove it when I did Xcode update.

As in the suggestion, the tool chain has to be removed from /Library/Developer/ToolChain/. In my case, there are two items in the direct:

$ ls
swift-2.2-SNAPSHOT-2015-12-10-a.xctoolchain
swift-latest.xctoolchain

The first one is a directry, and the second is a link to the directory. For safe case, I use Finder to the directory, and compress those two items first as Archive.zip. Then Remove them completely.

I have to quit Xcode and relaunch Xcode again to do clean build. This time warning error is gone.

My Update Xcode 12.0

The update process was painful. It toke long time to download. I got failure 2 twice.

I had Xcode update frustrating experience before. There was one time the updated Xcode version could not build my project. I had to rollback to old version from TimeMachine backup.

From that experience, I have been kept copy of previous Xcode to external disk first. Then I remove Xcode from Applications. In this way, this time I did clean installation of Xcode 12.0. Another reason is that I do not have enough space in my hard disk to do update. I had to remove old version to get more space.

This clean installation may missed the step to remove ToolChain.

References

• SO: How to fix DVTToolchain: Failed to load toolchain using Xcode command line tools?

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One-on-One Support from Apple

WWDC2020 was launched this week. In the past, WWDC conferences were all held in US. This year, because of COVID19 and social distance rules，WWDC is the first time on virtual web. The greatest news is that all Apple registered developers are all able to attend the WWDC without paying expensive registration, travel and hotel fees. This is first time Apple trying virtual WWDC.

On the first day, I watched the keynote speech yesterday. From my personal option, I think the virtual meeting is organized much more efficient and smooth, when transfering from one person to another. This can be done without any delay.

I watched Sean Allen's Swift News on YouTube. Among many topics about WWDC，he mentioned One-on-one Labs support, which was only available on site at WWDC. Now everything is on virtual. I quickly searched from Apple Developer's web page. It is true that one-on-one support is available on request. I made my request. I have been struggling on one UI issue for quite long time and still could not figure out any good solution. Within seconds, I got confirmation that my one-on-one support is scheduled tomorrow morning. That's awesome!

 


I have hight hope that I could get expert support directly from Apple to diagnose my issue and hope a solution would help to get the issue resolved.

Update on Jun 24 11MT: Just finished 1 on 1 labs support. I demonstrated my issue and showed what I have done in Xcode. The issue seems new to Apple support. He could not provide any solution and suggested me to submit a bug report on this issue.

The issue is that I have a screen with toolbar on bottom. There is one UIBarButton there. Most of time, the button shows normally. However, after a while, it would not visible when the screen brought up. I noticed that the issue is related to iPhone without physical Home button, ie, my Xr. The button still reacts to tap action even when it is invisible. It looks like that the button's tint color is as same as toolbar color, which causes button invisible.

References

• Apple Developer's Website: developer.apple.com
• Sean Allen's Swift News YouTube video：Swift News

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Use div for Table Layout in HTML

table HTML Tag has been in HTML for long time to show table-like layout. Now div is more powerful tag to display a block of text, and this can be used for table-like layout.

The basic concept is to use css styles as a way to instruct div to show block of text in table-like layout. After search on web, I found a couple ways to use div, and I place the correspoding ccs styles in Blogger's templates.

The following are some ccs classes in Blogger template:

/* -- no border table using div class */
.nbTable { 
  display: table;
  width: 100%;
} 
.nbTableRow {
  display: table-row;
}
.nbTableHeadRow {
  display: table-header-group; 
  font-weight: bold;
} 
.nbTableBody {
  display: table-row-group; 
} 
.nbTableFoot {
  display: table-footer-group; 
}
.nbTableCell, .nbTableHead {
  display: table-cell; 
}
.nbTableCell1Line, .nbTableHead1Line {
  display: table-cell;
  white-space: nowrap;
}

/* -- table with border using div class */
.bTable {
  display: table;
  width: 100%;
} 
.bTableRow {
  display: table-row;
}
.bTableCell, .rTableHead {
  display: table-cell;
  padding: 3px 10px;    
  border: 1px solid #999999;
}
.bTableCell1Line, .rTableHead1Line {
  display: table-cell;
  white-space: nowrap;
  padding: 3px 10px;
  border: 1px solid #999999;
}
.bTableHeadRow {
  display: table-header-group;
  background-color: #ddd;
  font-weight: bold;
}
.bTableFoot {
  display: table-footer-group;
  font-weight: bold;
  background-color: #ddd;
}
.bTableBody {
  display: table-row-group;
}

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Use VIM to Clean Up HTML

I have set up a blog at Blogger with more than one authors so that we can write our stories, observations about COVID-19. Some authors do not have any knowledge about HTML or how to write clean blogs there. As a result, the blogs they created contains massy HTML tags, either cause them frustration to edit text or inconsistent styles spreading blog text.





I am tech support person working hard behind scenes. One of my jobs is to clean up their blogs to remove unnecessary HTML tags. Here is one example how complexed HTML is:

VIM as Effective Tool

It is really tedious and time consuming to manually remove HTML paired tags. For example:

<span ...>...</span>

I realize that VIM is a great tool for help!

Here is the command to find out span paired block in HTML:

/<span\(\_.\{-}\)\@=\_.\{-}>

search for start patten <span any chars afterwards including mutilple lines till >.

Here is the result:





That's very exiting! With this confirmation test, it will be just line of VIM replace command to clean up span tags:

%s:<span\(\_.\{-}\)\@=\_.\{-}>::g  





More VIM command for finding and replacing


/<\/span\(\_.\{-}\)\@<=\_.\{-}> ## find </span>
:%s:<\/span\(\_.\{-}\)\@=\_.\{-}>::g ## replace </span>

/<div\(\_.\{-}\)\@<=\_.\{-}> ## find <div...>
:%s:<div\(\_.\{-}\)\@=\_.\{-}>::g ## replace <div>

/<\/div\(\_.\{-}\)\@<=\_.\{-}> ## find </div>
:%s:<\/div\(\_.\{-}\)\@=\_.\{-}>::g ## replace </div>

With above a few commands, I cleaned up HTML with great result!

References

• My previous blog (April 13, 2012): VIM Tip: Not Containing Pattern (3)
• My co-authors blog: Fighting Against COVID-19

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Blogger: Change Background Color & Text Size

I have a blog at Blogger. Recently my friends ask me if I could change the background color and increase font size for my posts. After search on web, soon I found solutions.

Change Background Color

First go to Theme, then Edit HTML.

Expand line 9, b: skin section.





Search for "post.background.color". You will find this as variable definition.





In my Blogger, it is located at line 32: Make a copy the variable first. Then you can make change:

1. <Variable name="post.background.color" description="Post Background" type="color" default="#ffffff" value="#353d4a"/>
2. <Variable name="post.background.colorDeleted" description="Post Background DELETE" type="color" default="#ffffff" value="#1c1c1c"/>

Make sure the description on line 2 is not as same as description on line 1. I think that the description is a key for variables.

This variable is used for the class of post.outer

Change Font Size

Another change I would like to do is to enlarge text size of post.  This is very easy to do. Find "post-body" in HTML template



In my Programmer's blog, I could not find post-body. The size of text is defined in body class.

References

• How to Change Background Color of logger post

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Story: A Traveler's COVID-19 Experience in Wuhan

Now it is pandemic critical time of COVID-19. I got an article in Chinese, a personal story of his COVID-19 in Wuhan China. I would like to share it in my programming blog. I will keep to update it with my translation as best as I can.

Personal Story of COVID-19 in Wuhan

I am a native of Wuhan and Shanghai. I got my undergraduate degree of Engineering in Huazhong University of Science and Technology in 1998. I am 43 years old. Now I run a software company in Shanghai. During my Chinese New Year's Eve in Wuhan with my family, I was suffering from neo-coronary pneumonia, ie, COVID-19, and then recovered. On January 26, 2020, I developed symptoms, and on March 14, I was confirmed to remove, and finally released from medical isolation. I have experienced the entire course of COVID-19.

As a science and tech person, I think that the COVID-19 is now a global pandemic. I try to summarize my experience and add some of the coping strategies I summarized during my sick for domestic and global friends in need as reference.

Notes on my Data

The cases covered in this article include:

• Just myself.
• Temporary Hospital(which is called as FangCai Hospital in Chinese) and I have 20 people in the same cabin from different administrative regions of Wuhan. My cabin number is 31st cabin of Wuhan Jianghan Fangbin Hospital.
• The rehabilitation station was 19 people on the same floor as me, from different hospitals and cabins. Specifically, it is the 6th floor of Building 2 of a rehabilitation station in Jiang'an District, Wuhan.

My explanation:

• The statements about specific conditions are all about me.
• For statistics, I will indicate which data is derived from the above sample.
• The check-in conditions for the FangCai Hospital are: at check-in, the body temperature must be below 37.5 degrees (normal body temperature) and the age must be under 65 years.
• The admission conditions of the rehabilitation station are: cured & discharged patients who meet the official discharge standards (negative nucleic acid test for two consecutive times, normal temperature for more than 5 days, etc.). For people discharged from a number of cabins, Raytheon Hill, and Vulcan Hill Hospital, the age is not required, and some are over 65 years old.

My Sick Period

Date	Description
2020/1/26	Felt fever in the morning
2020/1/29	Initial check at local community clinic, fevering not changed
2020/2/1	2nd check at the clinic, temperature remaining hight
2020/2/2	visited the specified fever hospital, and my CT showed high suspected symptom
2020/2/4	arranged nucleic acid test check by community clinic
2020/2/5	body temperature went back to normal, stayed at the norm
2020/2/6	received check result, positive.
2020/2/7	sent to Fangcai hospital by community to get isolation treatment
2020/2/29	confirmed recovery at Fangcai hospital
	transfered to rehabilitation station
2020/3/4	released from rehabilitation station, back to home.
Now	still need 14 days stay at home.

Key points from my own case, as well as other patient cases:

• I started with fever symptom on 1/26 and ended on 2/5. The duration: 11 days.
• Patients in the same cabin also have a fever duration of 1-2 weeks.
• I started with fever, and finally were negative for all three nucleic acid tests. My discharge conditions were met, and it took 32 days.
• Of 20 people in the same cabin, I was the 9th out of the cabin. I can roughly tell my typical indicators for my own case.

My sick development and key points

• At the beginning stage of high temperature, I felt very cold, just like in a big room without heating. I felt like the situation of taking off cloth for shower. Even I was in the bed with covers, I was shaking cold.
• My temperature went high at the period of 3rd to 5th day, about below 38.0. My under arm temperature was about 38.5. Before and after this period, my temperature was about 37 to 38.
• The time of my most difficult feeling was at about 4th or 5th day. No matter I stood or were in bed, I felt heavy in my chest. It was like finishing 1000m run in middle school, could not breath comfortably. This symptom may be like what medical experts described as breath tight. After passing 2 days, my chest felt much better. At that time, it was like my body immune system was back its strength from sleep. The tight breath was improved a lot.
• Patients with my in the same cabin all have similar feedback. With the help of medical helpers and moderate medicines, almost all of us fever went down.
• There are 20 patients in one cabin. After our body recovered to normal, basically none one showed fever except 1-2 people, who had fever 2 days before their coming. After treatment and caring, later they did not show any fever.
• During my fever initial days, I felt my body muscle sore and pain. After that, the symptom seems much better. After fever was gone, I have not felt muscle issue any more.
• Since the date I was in cabin, I got measurement of blood oxen level from my fingers and the number was good relatively, among 96-99%. Only a few were 93 or 94%. Nurses took measurements 4 times daily, during 22 days.
• After I was in cabin, I could tell my lung infection improving and ease, and I felt infections carried out by expelling sputum.
• During the period of 2nd to 15th of my fever, my cough was very obviously, with sputum. During the highest temperature of 3 days and 2-3 days afterwards, I could see blood threads in my sputum (not clog, I guess it may be from my lung damaged tiny vessels). After 2 days in cabin, my coughing was gone. Several days later, sputum was much less, and then stopped.
• During my stay in rehabilitation station out of cabin, we were in isolation stage. I stepped up to 6th floor. I felt breathing heavy(short break and heavy). Patients in the same floor had the same feeling. For reference, I was up to stairs every day during Aug to Sep in 2019. My speed up to 24 floors at about 5 minutes 20 seconds. I repeated 4 times (total to 96 floors), two groups in the morning and afternoon.

Cause

Unfortunately, I could not find out why for the moment.

When I was back to Wuhan, the disease were found in many places. I was very cautious and avoid out unnecessary, not contact people in large crowd. However, I was still caught the disease. I have 20 years senior programming experience, as well as many years of management and operations. My profession behave is very caution. I am with in top 1% in China. My case of COVID-19 only explains that this one is very hard to normal people to avoid. Many media news saying that it was spread by entering eyes, from shoes bottom were not enogh. I want to say that if you try to not getting this virus infection, you have to very very careful in everywhere, otherwise noway. Any careless or mistake would ruin all your protection efforts.

I try to get my caught reason as follows:

A. I might be infected by standing on street to have my breakfast (twice, about 20 minutes each time)

B. I was shopping (one time, about 30 minutes)

C. I was walking in our community area (3 times, 1 hour each time)

D. Our family build had some infected people. I might get caught during the time I was in elevator when I dump wastes (4-6 times a day, about 5 minutes)

My analysis

In all those cases, A, B, C I was with my daughter; D only myself.

My parents tested negative after my result was confirmed. My daughter was not infected. Only I was infected.

Based on above analysis, the most possibility is D.

Based on patients I was with in cabin:

• They were in cabin and rehabilitation station. Some were veterans. They have very good body, and they exercise a lot. They still were infected.
• Some are office workers, and they love exercise. Some got COVID-19 and passed away very quickly.
• Based on some news, there are some wellness trainers caught COVID-19 and passed away.

My conclusion:

• This virus is very easy to spread. Careless protection would not work.
• The infection time is very short, may be in just minutes.
• Don't go to area of crowd people, the risk would be very high.
• Be very careful in closed area such as elevator. 
• Choose to go to stairs if building is not too high, however, the stairs are also closed area. It may not safe neither.
• People with regular exercise and good health may also get infection. It seems that virus only infect weak people.

CT Images

See Chinese version for CT images. From the image, there are some cloud in clear lung, as I marked as red.

Medical experts summarize those area as cloud and unclear area. These area maybe infected.

Clinic medical person examined my CT image, and said very positively that this was typical case, 90% COVID-19.

CT image after removed

Unfortunately all films would have to sanitized and they were all collected back. When I was out of cabin, I could not take photos. I can only simply say that all the cloud area are disappeared or much less, with only small spots. Doctors from cabin said that this is called as absolved by itself.

Here is another more straightforward comparison pictures (see tree pictures in Chinese article).

Treatment of COVID-19

 The treatment is in two stages, before cabin, and in cabin. In rehabilitation station, the condition is simple and no treatment service were provided.

Up to the time being, there is no official announcement of effective treatment medicines. I am not medical expert, nor I have any medical background. Therefore, my personal views may misleading you. Here I only objectively choose the treatment medical helpers provided for me, as for your reference. Please note that any medical treatment is only for specific case, and cannot be applied as general. Follow your medical doctors instruction when apply medicine.

During my treatment, the basics what I did are:

1. keep positive attitude
2. trust medical export's ability and professional skills, follow their advice to take medicines
3. corporate with nurses routine checks and instructions

Treatment in cabin

Before cain, my treatment was mainly to follow medical instructions to take medicines.

During my community visits, I was not identified if I was normal fever or COVID-19. My treatment was mainly to reduce fever. I took fever medicines, anti-infection medicines, Lianhua medicine for ease virus. Because those methods were not for COVID-19, my fever not improved.

After that period, medical export in community realized that normal medicine seems not working. They decided to check if I was in COVID-19, and sent me to specified Wuhan Hospital to check.

At the hospital, I was determined mostly likely as COVID-19 based on CT image. They my treatment was focused on the virus. My personal feeling was that the result was very obvious. I started to take medicine on Feb 2. On Feb 5, my fever was basically released. See pictures of medicines (in Chinese article).

The last two are most effective. After taking with hotter, I felt a little bit sweat afterwards. I got those medicines from Hankou Hospital. All those medicines are within medical insurance.

Treatment in cabin

The treatment in cabin is the mixture of Western and Chinese medicines.

• On the 1st date in cabin, doctors described us normal anti virus medicines (such as Abidol), as well as Chinese herb medicine(Lianhua anti virus capsues).
• One week later, based on national announcement of medical treatment, we took the 2nd description, 2 bags daily, patient made decision to take or not.
• 10 days later, doctors advised us to stop western medicines. We continued 2nd plan, 2 bags daily. They also provided more milk and other nutritions.

As I mentioned above, after I was in cabin, my fever was gone and blood oxygen level back to normal. With much less symptoms and the continuation of medicines I did not seem obviously.

Medical Expenses

My house registration and insurance are belonging to Shanghai. The expense before COVID-19 was on myself, in total 1983.42.

Date	Hospital	Item	Fees	Sub
2020/1/29	Community Clinic	Diag fee	20.5
		Medicine	227.45	247.84
2020/2/1	Clinic	Diag	20.5
		Medicine	186.62	207.12
2020/2/2	Hankou H.	Reg	free
		Blood check	449
		CT	359
		Treatment	36
		Med	346.98	1190.98
2020/2/7	Hankou H.	Med	337.48	337.48
		Total:		1983.42

I purchased commercial insurance, and I claimed it after I was released. My insurance paid 60% of my claim (about 1190yuan). For remaining amont (about 790yuan), I will check it when I get back to Shanghai. I think that it may be covered by normal insurance coverage at outside locations.

All my cabin and rehabilitation fees, all treatment, check, CT, food, daily expenses could be free. Up to the time being, I have not paid for those. I have not been asked to pay my cabin fees, nor any forms. However, I am not sure if my Shanghai insurance would refuse any payments. If any, I would list them and let my friends know.

Nutrition to COVID-19 Patients

For COVID-19 infection, nutritions are needed for patients to help them to quickly recover. I have the following list about nutrition concern:

• Cooked eggs, 1 or 2 for breakfast and. There are rich nutritions in eggs, with protein. This will provide sufficient bullets for body to fight virus. At cabin and rehabilitation, at least one boiled egg is supplied.
• Chicken soup. Hot soup helps to bring body strength back, help to sweat. With some salts, it adds electrolytes.
• Balanced lunch. noon and evening meals in cabin and rehabilitation are supplied based on nutrition recommendations. Unfortunately I could find resources about it at that time. Based on my observation, there are meat, chicken, fish and shrimps for proteins, and sufficient vegs.
• Seasonal fruits to supplement vitamins, helping to fight free-radicals.
• Milk and sour milk, as protein and calciums supplements.
• Small meals. small ones are almost as same as noon and evening meals, not much variations. In order to help patients to recover quicker, patients ate a little more than normal.

Because of different tastes among individuals, my observation is based food in Wuhan food style. Other places should refer to local nutrition experts recommendations.

Personal Supply Preperation

how much to prepare?

Based on my own observation, more people are less severe patients, and their treatment period is about 30 days. Taking isolation into consideration, it should prepare personal supplies for 60 days.

Basic supply

Location administrations provide guidelines for supplies, including:

1. sufficient food: meals, vegs, meat, eggs, frozen foods, and others.
2. cleaning products, hand gel (or 75% alcohol), soap, and others, one package for one person in a family.
3. masks, sufficient for use
4. sanitizers, carbon dioxide pills, 84 disinfectant, former is better to long time storage.
5. home used medical equipments, temperature measure device, finger oxygen measure device, blood pressure measure device, and others.
6. sufficient medicines for chronic illness if you are depend on them, such as high pressure, diabetes, insulin injection devices.
7. toilet and hygiene paper.

Others

Besides above recommendations, based on my own and other patient cases, you may consider to prepare following supplies.

1. strongly recommend to bring some physiology books, basic or middle levels. They will help you pre, during, and post periods.
2. if you don't have insurance, you should consider to buy some health insurance. Pay attention to starting date of insurance.
3. personal care products, at least 2 sets, such as finger nail cutter, shavers, swabs.
4. women hygiene products, at least for 2 months.
5. baby supplies if you have baby
6. Hair cutter
7. charger and wires
8. medicines for eyes, such as erythromycin eye ointment, ofloxacin drops. 
9. paper, pen and notes.
10. several sets of one time use rain coat. if passing disinfection spray, normal rain coats are good enough.
11. fresh preserve bags
12. one cell, optional
13. oxygen breath machine for senior people, about 3000 yuan cost, optional
14. eye protection glasses, optional
15. bicycle or electric slide board, for shot distance emergency use

Supplies for isolation

following supplies are very useful if being isolated:

1. swissarmy utility. This device can be used to peel fruits, cut plastic bags, and fixing small items. This is really a handy device. If you don't have, you can bring fruit peeler or knigh. Those tools were allowed duing my stays. Personally, I think they are very useful.
2. charger and wires
3. one thermal cup and one cub, for taking medicines or cooling waters.
4. paper, pen, and note books.
5. carryon computer. The period of isolation was very boring. The laptop may help you to spend times.
6. earphone plugs and eye covers. Those items were really helpful for sleeping and quick recovery. If you cannot sleep in short time, those items are good for you.
7. toilet paper. Normally all stations have papers, but you may find it helpful in emergency.
8. slipers. One time use or normal ones are good and convenient. But you should be careful when floor are wet or slippery (wash room, toilets), very dangerous there.
9. personal care items such as nail cutter, shaver, and swabs.
10. women use items
11. a lots of fresh preserve bags, large size and thick ones.
12. bring a book. you can read, or use it to cover convenient noddles, or as seat pad, many usages.

I recommend you to prepare those supplies now. Prepare two sets, one for you and one for family.

Self Psychological Adjustment and Recovery

I was very serious to read psychological books, on how to cope with COVID-19. Some one already provide a solution: the killer is not virus, but the panic and anxiety by the virus.

In case of being caught by the virus, either you or your friends(you may skip this section if you not by the virus), my personal self psychological adjustment for COVID-19 is as follows. I use the title of a well-known book as this section header. I think it can be also called as self-cultivation of COVID-19 patients.

1. I agree with psychological release, instead of intervention. These two methods, for people who don't know, may think they are the same. In fact, they are very different in reality.
2. No matter how long in treatment or isolation, or self status suddenly falling to bottom, you should always keep optimistic. Try to adapt to it, and don't just complain. If possible, try to change your context.
3. Tell out when you cannot hold things. You should use simply and clear words to tell direct administrators, or relevant, or people who has influence. Actually, every one is willing to help you. Communication is necessary. Don't hesitate, depressed, or would bother others.
4. The most important thing to do is to maintain good sleep.
5.  After 8:00pm, you could play games, don't watch mass media news about the virus, which may affect your sleep.
6. Image a way to guide your to sleep. What I did to watch math of university level. I remembered that I would go to sleep when I saw those questions. Now I could use this strategy. You could learn something when you cannot sleep, or fall in sleep.
7. Friends around you all would like to talk. Try to talk to them. This could help you to ease stressed mood. Keep away 1 meter away, just remember this. Every one should wear masks. Keep further away if not with mask.

Conclusion

I close my strategies towards COVID-19. I hope every one have most careful protection measures. It is better not being caught by the virus. In case of you infected, I hope you will overcome fear thoughts, be positive.

I think I am a ordinary person, just like you. I have managed to pass over this journey and fully recovered, same will be you. Be strong!

I hope that my experience and this summary could help you. If you have any questions, or want to know more, please leave your comments. I will try my best to answer your questions.

References

• Personal Story of COVID-19 in Wuhan (Chinese)

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Conditional Compilation in Xcode

Recently I have interest in C/C++ #ifdef macro features in Swift. The main reason is that I have some debug codes through out my project for test and debug purpose. For example, I like to add deinit destruction with print() codes in classes to test memory leaks. Since those destructors have no purpose to clean up resources, I have to comment out them in production compilation.

In Swift, there are some conditional compilation features to including or excluding block of codes. For example, the following codes using #available to test if the current iOS matches required version.

if #available(iOS 11.0, *)

Further investigation, I find out that Swift does support #if statements to provide conditional compilation. The following are steps to implement the feature.

Define Custom Compilation Flags

The first step is to define customized complication flags in Xcode project. In the section of Build Settings, find Swift Compiler - Custom Flags (make sure All and Combined are enabled on top tab bar).



Then, you can add custom flag variables. Here are two examples of DEBUG_PRINT and DEBUG_DEINIT. For each flag, add -D before it, like "-D DEBUG_DEINIT -D DEBUG_PRINT"



Note: in the picture, I defined those two with _X as suffix to disable them. If I want to enable them in compilation, I remove _X.

Use Custom Compilation Flags in Swift

To use #if feature, it is quite straightforward. For example, there is the conditional compilation block for destructor:

1. // MARK: - CTOR
2. #if DEBUG_DEINIT
3. deinit {
4.  Logger.debug() {
5.    String("\(CopyMoveViewController.className) deinit")
6.  }
7. }
8. #endif

and here is an example of conditional compilation block for some codes:

1. class Logger {
2.  ...
3.  static func debug(_ message: () -> String) {
4.    #if DEBUG_PRINT
5.    print(message())
6.    #elseif DEBUG_DEINIT
7.    print(message())
8.    #endif
9.  }
10. }

Now I don't need to comment out some debug codes when I need to compile my project to production release target. The only thing I need to do is to disable those flags in my Xcode project file.

References

• Swift Documention on Compiler Control Statements
• SO's QA: In absence of preprocessor macros, is there a way to define practical scheme specific flags at project level in Xcode project

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Update to Xcode 11.3

I have been working on iOS projects with Xcode 11.1 for quite long time. Previously, I tried to update to 11.2. However, I experienced crashing issues after I compiled my project with Xcode. The problem was text editor. Each time when I tried to enter edit mode with text field UI, the app suddenly crashed. That was really bad experience.

I had to restore back to 11.1 version. Fortunately, I have Time Machine backup. From there, I restored Xcode 11.1.

Xcode 11.3 was released, but I did not update right away. Until I tried to compile my project to my iPhone with iOS 13. I got message that I had to move up to newer Xcode supporting iOS 13. I have no choice to move  on.

Update from App Store is also a pain. I tried for several days to update but I got failure each time. There is no reason given, and each time it took long period to download package, 7.8GB. That was really frustrating.

Yesterday a idea came up to my mind. Why not to go to Apple developer site to get Xcode? There must be Xcode 11.3 package just for download only. I went to the site and Xcode.xip is in the section of More(Beta, Release and More 3 sections). This makes me update much easier because it is the straight download.

After downloading, I clicked on the package. Soon I got a message of "not enough space on destination". That's why. The disk space is always problem on MacBookAir/Pro. What I did is to move out existing Xcode from Application to external disk. Finally I got Xcode 11.3 successfully installed!

So far, I have no issues with this version, and I could run my app on my iPhone for testing.

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