Unable to create description in descriptionForLayoutAttribute_layoutItem_coefficient. Something is nil

Unable to create description in descriptionForLayoutAttribute_layoutItem_coefficient. Something is nil


Symptom: Normal but crash in iOS 7 device.

Possible reason : Use some “Baseline” constraints (Only supported after iOS 8) in storyboard.

Solution : Remove any “Baseline” constraints of that page crashed in storyboard.

Posted in iOS development | Leave a comment

XCode SVN is not under version control

That is the keyword I Googled for solution and no luck.

I’m too old to learn new source control mechanism like Git so I stuck on SVN with XCode.

It works perfect usually but sometimes it show “xxx is not under version control”.

For me, the reason is some special character in file name , in my case , the @ character.

I googled and tried to fixed this issue but no luck.

And today, finally, I solved this issue with one single step, simple and straight.

Open “Terminal” application, go to the project folder and keyin this

svn commit -m “Happy SVN”

And you’ll see all the files (including file name with @ character) are committed successfully.

I don’t know why the commit won’t succeed in XCode, but I’m happy that it works in command line mode.


Update on 2016/03/02:

Sometimes you have to make those @xx.png files the Add status (with A in the right) in Xcode first before you do the command-line svn commit.

Posted in iOS development | Tagged , , , , , , | Leave a comment

Custom URL schemes practice

Let’s define something in this scenario :

1.Receiver app – to be invoked via custom URL

2.Sender app – who wants to invoke the app

3.Custom URL scheme – define as “happygo”



For Receiver app, here’s what to do:

1.Define the url scheme in Project/Targets/Info/URL Types as follow

螢幕快照 2016-02-04 下午12.20.51

2.AppDelegate.m – Two methods to be implemented.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
 return YES;    //must return YES
- (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation {
 //Check if the scheme was valid
 if ([[url scheme] isEqualToString:@"happygo"]) {
 NSString *query = [url query];
 NSArray *queryComponents = [query componentsSeparatedByString:@"&"];

 for (int i=0; i<[queryComponents count]; i++) {
 NSArray *oneParam = [[queryComponents objectAtIndex:i] componentsSeparatedByString:@"="];
 NSString *sValue = @"";
 NSString *sKey = [oneParam objectAtIndex:0];
 if (oneParam.count==2) {
 sValue = [oneParam objectAtIndex:1];
 //Here is what you want to do, write here.
 return TRUE;   //return TRUE because of valid scheme
 return FALSE;   //invalid scheme, skip process



For Sender app, here’s what to do :

1.Add the following to info.plist


2.Invoke the receiver app via URL form, sample source code as follow

NSString *sURL = [NSString stringWithFormat:@"happygo://www.domain.com?name=Good&phone=123123"];
 NSURL *myURL = [NSURL URLWithString:sURL];

 if ([[UIApplication sharedApplication] canOpenURL:myURL]) {
 [[UIApplication sharedApplication] openURL:myURL];
 } else {
 NSLog(@"--bad url--");

Actually, you can even invoke the app via Safari Browser.

Just input the URL in Safari, press GO, and the receiver app will be invoked.

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iOS Watchkit Development – paired device unavailable for development

I had this problem twice, I googled the same article to do the same actions to fix.

Here I wrote down to remember myself.

Error : “paired device unavailable for development” showed in XCode when new to Apple Watch

Fix steps :

  1. Unpair my watch
  2. Reboot both iPhone and apple watch
  3. Pair them again, and setup my watch as a new one
  4. Plug (unplug first) iPhone to Mac
  5. On apple watch, say Trust the computer when it asks
  6. Unplug and plug again
  7. Close and open XCode
  8. Open the project and wait a few seconds

Good luck.

Posted in iOS development | 3 Comments

Icon only UITabbar, no title at all.

1.Clear the title attribute to empty.

2.Set the Image Insect attribute of the Tabbar item as follow


And you’re good to go.

Happy Tabbaring…

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Set UITabbar tintColor via StoryBoard

I found that it’s really weird to set UITabbar tintColor.

It won’t work if you change the Tint attribute in the View section.


You have to add the attribute by yourself to make it work. Check this out.


Happy Tabbaring !!

Posted in iOS development | Leave a comment

Add existed XCode project to SVN repository

I’ve been bothered by this issue for a long time.

And finally I’d decide to find the best practice today to do this job.

Here are the steps:

Step 1.

Create SVN repository, for example, http://svn.domain.com/myrepo

Step 2.

Create XCode project, Assume the project path is Documents/iosprojects/milkshaker

Step 3.

Open OS X app Terminal  which is command line mode.

Step 4.

In terminal, cd to the parent directory of your project directory (Documents/iosprojects in this example)

cd /Users/yourname/Documents/iosprojects

Step 5.

The most import step, svn import (NOT ADD) as following command

svn import -m “New Import milkshaker/ http://svn.domain.com/myrepo

The syntax is

svn import -m “<remark message> <project directory>/ <SVN URL>

Key in the userid and password and you’re good to go.

Step 6.

After step 5 was done.

Open XCode app, try Source control->Check out

Key in the SVN URL, userid and password to checkout the project to local directory.


That would be all I want to share, happy SVNing !!

Posted in Misc | Leave a comment

UILabel 動態高度 Dynamic Height

UITableViewCell 有 heightForRowAtIndexPath 可以指定


若是「想以文字內容決定 UILabel 的高度」


先用「文字,字型和寬度」(這點要事先決定,不然沒辦法算)計算出 UILabel 的高度

然後再用這個算出來的高度去 initWithFrame



+(float) getHeightForText:(NSString*) text withFont:(UIFont*) font andWidth:(float)width {
CGSize constraint = CGSizeMake(width , 20000.0f);
CGSize title_size;
float totalHeight;

SEL selector = @selector(boundingRectWithSize:options:attributes:context:);
if ([text respondsToSelector:selector]) {
title_size = [text boundingRectWithSize:constraint
attributes:@{ NSFontAttributeName : font }

totalHeight = ceil(title_size.height);
} else {
title_size = [text sizeWithFont:font
totalHeight = title_size.height ;

CGFloat height = MAX(totalHeight, 40.0f);
return height;

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不要再抓手機型號了,因為 iPhone6/6P 有 Zoom 果實能力


很有可能你是因為想判斷 iPhone 的不同型號






我落入了「判斷手機型號,然後寫不同的顯示 code」的地獄深淵







iPhone 6/6P 還提供了 Zoom 的功能(註)

(分成一般顯示和 Zoom 顯示)

iPhone 6Plus 開啟 Zoom 模式,就等同 iPhone 6 的顯示方式

iPhone 6 開啟 Zoom 模式,就等同 iPhone 5S 的顯示方式






#define IS_IPAD (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
#define IS_IPHONE (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
#define IS_RETINA ([[UIScreen mainScreen] scale] >= 2.0)

#define SCREEN_WIDTH ([[UIScreen mainScreen] bounds].size.width)
#define SCREEN_HEIGHT ([[UIScreen mainScreen] bounds].size.height)



if (IS_IPHONE_6P) {



else if (IS_IPHONE_6) {



註:這篇文章將 iPhone 的解析度解釋的非常清楚,大推

要想徹底搞清楚 iPhone 的解析度是怎麼回事,就看這篇

Posted in Misc | Leave a comment

GoGo Board v2.2 is ready in AppStore

– Simple marquee banner with scrolling text
– Easy to use
– Decide what color the text is by yourself
– Decide the background color by yourself
– Decide the scrolling speed

This app was suitable for every kinds of situations that you can’t talk.
Such as meeting, movie theatre, restaurant … etc.

Download FREE (and no in app purchase) via Appstore Link

Posted in 加油板跑馬燈 | Leave a comment