首先如果想要macOS在 terminal 裡正確顯示 right-to-left (RTL or dextrosinistral) 可以服用下列指令：

1. Press Command+Space and type Terminal and press enter/return key.
2. Run in Terminal app:
   ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" < /dev/null 2> /dev/null
   and press enter/return key. 
   If the screen prompts you to enter a password, please enter your Mac’s user password to continue. When you type the password, it won’t be displayed on screen, but the system would accept it. So just type your password and press ENTER/RETURN key. Then wait for the command to finish.
3. Run:
   brew install fribidi

對雙向文本（Bi-directional text）的支援，小的文字編輯軟體可能只有支援一半，例如：sublime 這套軟體，在整份檔案都是 bidi 情況下，是可以支援，但交叉顯示時，顯示就會出錯，會相反顯示，我也因此花了很多冤枉的時間在除錯。

除了小編輯器會有問題，程式語言python 3在處理bidi 的字串也會有問題，做法很簡單，遇到 bidi text 自己手動反轉即可，附上字串反轉副程式：

def reverse_i(s):
    r = ''
    for c in s:
            r = c + r
    return r

在sublime 上會發生一些「神奇的」錯誤，就是畫面上顯示的阿拉伯文是正確的，但copy/paste 到 xcode 或 browser 上看時，會是相反的字串，所以要知道自己有沒有處理正確，只要都使用大公司推出的文字編輯器就不會有問題。如果用不習慣大公司的文字編輯器，請記得最後要貼到瀏覽器上做驗證，例如：

Wiki：
https://en.wikipedia.org/wiki/Bi-directional_text

雙向文本
https://zh.wikipedia.org/wiki/%E9%9B%99%E5%90%91%E6%96%87%E7%A8%BF

@import GoogleMobileAds;

@interface ViewController ()

@property(nonatomic, strong) GADBannerView *bannerView;

@end

@implementation ViewController

- (void)viewDidLoad {
  [super viewDidLoad];
  
  // In this case, we instantiate the banner with desired ad size.
  self.bannerView = [[GADBannerView alloc]
      initWithAdSize:kGADAdSizeBanner];

  [self addBannerViewToView:self.bannerView];
}

- (void)addBannerViewToView:(UIView *)bannerView {
  bannerView.translatesAutoresizingMaskIntoConstraints = NO;
  [self.view addSubview:bannerView];
  [self.view addConstraints:@[
    [NSLayoutConstraint constraintWithItem:bannerView
                               attribute:NSLayoutAttributeBottom
                               relatedBy:NSLayoutRelationEqual
                                  toItem:self.bottomLayoutGuide
                               attribute:NSLayoutAttributeTop
                              multiplier:1
                                constant:0],
    [NSLayoutConstraint constraintWithItem:bannerView
                               attribute:NSLayoutAttributeCenterX
                               relatedBy:NSLayoutRelationEqual
                                  toItem:self.view
                               attribute:NSLayoutAttributeCenterX
                              multiplier:1
                                constant:0]
                                ]];
}
  

@end

結果顯示錯誤訊息：

NSLayoutConstraint for (null): Constraint must contain a first layout item

發生的原因是，直接套用了英文版裡的範例會出錯，改服用中文版裡的範例和指引就OK了。中文版的解法是：
https://developers.google.com/mobile-ads-sdk/docs/admob/ios/quick-start?hl=zh-tw

1：設定 Storyboard 裡的元件。

開啟 Main.storyboard。在右下角的 Object library (物件程式庫)中，搜尋 UIView，然後將 UIView 元素拖曳至檢視控制器。接著在右上角的 Identity inspector (身份偵測程式)中，將這個檢視設為自訂類別 GADBannerView。

2：不需要 create object 進 GADBannerView，直接做 adUnitID assign 和 loadRequest.

- (void)viewDidLoad {
  [super viewDidLoad];

  NSLog(@"Google Mobile Ads SDK version: %@", [GADRequest sdkVersion]);
  self.bannerView.adUnitID = @"ca-app-pub-3940256099942544/2934735716";
  self.bannerView.rootViewController = self;
  [self.bannerView loadRequest:[GADRequest request]];
}

問題：違反不當廣告政策

您的應用程式內顯示的廣告除了必須符合我們的政策規定，還必須針對目標對象提供適當內容。舉例來說，如果應用程式的內容分級適用對象為未成年人，則不可放送含有兒童不宜內容或服務的廣告。

解法：

https://support.google.com/admob/answer/7562142?hl=zh-Hant&ref_topic=7384665

數位內容標籤

AdMob 會使用數位內容標籤，就廣告對不同目標對象的適合程度進行分級。這類標籤類似於其他機構組織為電影或電玩遊戲所設定的內容分級。

數位內容標籤依定義分為下列幾種：

• G：內容適合一般觀眾 (包括闔家皆宜的內容)
• PG：內容適合大多數的觀眾 (需有家長監護)
• T：內容適合青少年及較年長的觀眾
• MA：內容只適合成年觀眾

Google Play 和 Apple App Store 各有專屬的分級和標籤套用方式，用以判定內容對不同年齡層的適合程度。請參閱下表，瞭解您應用程式目標對象所對應的數位內容標籤。

程式：
provide targeting information to an ad request.

https://developers.google.com/admob/android/targeting#child-directed_setting

Bundle extras = new Bundle();
extras.putString("max_ad_content_rating", "MA");

AdRequest request = new AdRequest.Builder()
        .addNetworkExtrasBundle(AdMobAdapter.class, extras)
        .build();

 

完整範例：
https://github.com/googleads/googleads-mobile-android-examples/blob/master/java/advanced/APIDemo/app/src/main/java/com/google/android/gms/example/apidemo/AdMobAdTargetingFragment.java

From iOS 8 we can use the new isOperatingSystemAtLeastVersion method on NSProcessInfo

   NSOperatingSystemVersion ios8_0_1 = (NSOperatingSystemVersion){8, 0, 1};
   if ([[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion:ios8_0_1]) {
      // iOS 8.0.1 and above logic
   } else {
      // iOS 8.0.0 and below logic
   }

Beware that this will crash on iOS 7, as the API didn’t exist prior to iOS 8. If you’re supporting iOS 7 and below, you can safely perform the check with

if ([NSProcessInfo instancesRespondToSelector:@selector(isOperatingSystemAtLeastVersion:)]) {
  // conditionally check for any version >= iOS 8 using 'isOperatingSystemAtLeastVersion'
} else {
  // we're on iOS 7 or below
}

解法2號：

Best current version, without need to deal with numeric search within NSString is to define macros(See original answer: Check iPhone iOS Version)

Those macros do exist in github, see: https://github.com/carlj/CJAMacros/blob/master/CJAMacros/CJAMacros.h

Like this:

#define SYSTEM_VERSION_EQUAL_TO(v)                  ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedSame)
#define SYSTEM_VERSION_GREATER_THAN(v)              ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedDescending)
#define SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(v)  ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedAscending)
#define SYSTEM_VERSION_LESS_THAN(v)                 ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedAscending)
#define SYSTEM_VERSION_LESS_THAN_OR_EQUAL_TO(v)     ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedDescending)

and use them like this:

if (SYSTEM_VERSION_LESS_THAN(@"5.0")) {
    // code here
}

if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(@"6.0")) {
    // code here
}

Outdated version below

to get OS version:

[[UIDevice currentDevice] systemVersion]

returns string, which can be turned into int/float via

-[NSString floatValue]
-[NSString intValue]

like this

Both values (floatValue, intValue) will be stripped due to its type, 5.0.1 will become 5.0 or 5 (float or int), for comparing precisely, you will have to separate it to array of INTs check accepted answer here: Check iPhone iOS Version

NSString *ver = [[UIDevice currentDevice] systemVersion];
int ver_int = [ver intValue];
float ver_float = [ver floatValue];

and compare like this

NSLog(@"System Version is %@",[[UIDevice currentDevice] systemVersion]);
NSString *ver = [[UIDevice currentDevice] systemVersion];
float ver_float = [ver floatValue];
if (ver_float < 5.0) return false;

For Swift 4.0 syntax

below example is just checking if the device is of iOS11 or greater version.

let systemVersion = UIDevice.current.systemVersion
if systemVersion.cgFloatValue >= 11.0 {
    //"for ios 11"
  }
else{
   //"ios below 11")
  }

解法3號：

if (NSClassFromString(@"UIPopoverController")) {
    // Do something
}

if ([LAContext class]) {
    // Do something
}

if ([CLLocationManager headingAvailable]) {
    // Do something
}

if (&UIApplicationOpenSettingsURLString != NULL) {
    [[UIApplication sharedApplication] openURL:[NSURL URLWithString:UIApplicationOpenSettingsURLString]];
}

- (BOOL)isOperatingSystemAtLeastVersion:(NSOperatingSystemVersion)version

// A system version of 3.1 or greater is required to use CADisplayLink. The NSTimer
// class is used as fallback when it isn't available.
NSString *reqSysVer = @"3.1";
NSString *currSysVer = [[UIDevice currentDevice] systemVersion];
if ([currSysVer compare:reqSysVer options:NSNumericSearch] != NSOrderedAscending) {
    displayLinkSupported = TRUE;
}

Provisioning profile "xxx" doesn't include signing certificate "iPhone Developer: xxx(xxx)".

我们需要清除Mac中的provisioning profile，在keychain 裡刪除相關 的 Keys 和 Certificates，然后再到xcode-preferences-account-detail裡重新點「Download Manually Profiles」。

如果還是build 不過，大多數的情況是，需要给automatically signing 打上勾，就ok了，一键解决。

如果有曾勾選過 “always allow codesign”  的按鈕在build app 時，如果還是有問題，則需要重開機一次，才能重新彈出 codesign 的對話框，才能針對新的帳號做授權。

ld: symbol(s) not found for architecture armv7

使用了 pod update 指令，還是無法解決，訊息如下：

CocoaPods 1.5.3 is available.
To update use: `sudo gem install cocoapods`

For more information, see https://blog.cocoapods.org and the CHANGELOG for this version at https://github.com/CocoaPods/CocoaPods/releases/tag/1.5.3

Analyzing dependencies
Pre-downloading: `SVProgressHUD` from `https://github.com/SVProgressHUD/SVProgressHUD.git`
Downloading dependencies
Installing SVProgressHUD 2.2.5 (was 2.2.5)
Generating Pods project
Integrating client project
Sending stats
Pod installation complete! There is 1 dependency from the Podfile and 1 total pod installed.

[!] The `EGeofence [Debug]` target overrides the `OTHER_LDFLAGS` build setting defined in `Pods/Target Support Files/Pods-EGeofence/Pods-EGeofence.debug.xcconfig'. This can lead to problems with the CocoaPods installation
    - Use the `$(inherited)` flag, or
    - Remove the build settings from the target.

[!] The `EGeofence [Release]` target overrides the `OTHER_LDFLAGS` build setting defined in `Pods/Target Support Files/Pods-EGeofence/Pods-EGeofence.release.xcconfig'. This can lead to problems with the CocoaPods installation
    - Use the `$(inherited)` flag, or
    - Remove the build settings from the target.

我是在 “General” – “Linked Frameworks and Libraries” 裡加入，即可正常 build.

Apple 官方文章：

https://developer.apple.com/library/content/samplecode/sc2279/Introduction/Intro.html

Managed App Configuration

“ManagedAppConfig” demonstrates how to implement managed app configuration and feedback support in an iOS application. This functionality allows a Mobile Device Management (MDM) server to push down a dictionary into the managed app’s NSUserDefaults for the purposes of remotely configuring settings. Also, feedback (such as critical errors) can be written by the app into NSUserDefaults which can then be queried by an MDM server. This is a powerful mechanism enterprise and educational institutions can use to remotely configure managed applications from a centralized MDM server.

Apple 官方的 sample code：

– (void)readDefaultsValues {

    NSDictionary *serverConfig = [[NSUserDefaults standardUserDefaults] dictionaryForKey:kConfigurationKey];

    NSString *serverURLString = serverConfig[kConfigurationServerURLKey];

    // Data coming from MDM server should be validated before use.

    // If validation fails, be sure to set a sensible default value as a fallback, even if it is nil.

    if (serverURLString && [serverURLString isKindOfClass:[NSString class]]) {

        self.serverURLUILabel.text = serverURLString;

    } else {

        self.serverURLUILabel.text = @”http://foo.bar”;

    }

    NSNumber *disableCloudDocumentSync = serverConfig[kConfigurationDisableCloudDocumentSyncKey];

    if (disableCloudDocumentSync && [disableCloudDocumentSync isKindOfClass:[NSNumber class]]) {

        self.cloudDocumentSyncEnabledSwitch.on = ![disableCloudDocumentSync boolValue];

    } else {

        self.cloudDocumentSyncEnabledSwitch.on = YES;

    }

    // Fetch the success and failure count values from NSUserDefaults to display.

    // Data validation for feedback values is a good idea, in case the application wrote out an unexpected value.

    NSDictionary *feedback = [[NSUserDefaults standardUserDefaults] dictionaryForKey:kFeedbackKey];

    NSNumber *successCount = feedback[kFeedbackSuccessCountKey];

    if (successCount && [successCount isKindOfClass:[NSNumber class]]) {

        self.successCount = [successCount unsignedIntegerValue];

    } else {

        self.successCount = 0;

    }

    self.successUILabel.text = [NSString stringWithFormat:@”%lu”, (unsigned long)self.successCount];

    NSNumber *failureCount = feedback[kFeedbackFailureCountKey];

    if (failureCount && [failureCount isKindOfClass:[NSNumber class]]) {

        self.failureCount = [failureCount unsignedIntegerValue];

    } else {

        self.failureCount = 0;

    }

    self.failureUILabel.text = [NSString stringWithFormat:@”%lu”, (unsigned long)self.failureCount];

}

[self.navigationItem setHidesBackButton:YES];
[self.navigationItem setTitle:NSLocalizedString(@"Camera",@"")];

後來增加了 Tab bar 後，左上角的 back 就出來了，set title 也失敗。類似的失敗畫面：

解法如下：

You can set all the UITabBar icons in an easy way. You can do this in your viewWillAppear:method:

[[self.tabBarController.tabBar.items objectAtIndex:0] setTitle:NSLocalizedString(@"BotonMapas", @"comment")];

[[self.tabBarController.tabBar.items objectAtIndex:1] setTitle:NSLocalizedString(@"BotonRA", @"comment")];

[[self.tabBarController.tabBar.items objectAtIndex:2] setTitle:NSLocalizedString(@"BotonEstado", @"comment")];

[[self.tabBarController.tabBar.items objectAtIndex:3] setTitle:NSLocalizedString(@"LabelInfo", @"comment")];

Swift 3.1 Solution

self.tabBarController?.tabBar.items?[0].title = NSLocalizedString("BotonMapas", comment: "comment")
self.tabBarController?.tabBar.items?[1].title = NSLocalizedString("BotonRA", comment: "comment")
self.tabBarController?.tabBar.items?[2].title = NSLocalizedString("BotonEstado", comment: "comment")
self.tabBarController?.tabBar.items?[3].title = NSLocalizedString("LabelInfo", comment: "comment")

You can set all the UITabBar icons in an easy way. You can do this in your viewWillAppear:method:

[[self.tabBarController.tabBar.items objectAtIndex:0] setTitle:NSLocalizedString(@"BotonMapas", @"comment")];

[[self.tabBarController.tabBar.items objectAtIndex:1] setTitle:NSLocalizedString(@"BotonRA", @"comment")];

[[self.tabBarController.tabBar.items objectAtIndex:2] setTitle:NSLocalizedString(@"BotonEstado", @"comment")];

[[self.tabBarController.tabBar.items objectAtIndex:3] setTitle:NSLocalizedString(@"LabelInfo", @"comment")];

Swift 3.1 Solution

self.tabBarController?.tabBar.items?[0].title = NSLocalizedString("BotonMapas", comment: "comment")
self.tabBarController?.tabBar.items?[1].title = NSLocalizedString("BotonRA", comment: "comment")
self.tabBarController?.tabBar.items?[2].title = NSLocalizedString("BotonEstado", comment: "comment")
self.tabBarController?.tabBar.items?[3].title = NSLocalizedString("LabelInfo", comment: "comment")

NSURLSession *session = [NSURLSession sharedSession];

NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration];

As you’re using them, they’re functionally very similar. But using sharedSession doesn’t give you the ability to customize the NSURLSessionConfiguration (e.g. tweak the cache, custom headers, etc.) nor use the delegate-based rendition of NSURLSession.

說明：一般的情況下使用 sharedSession 應該就ok, 問題是出問題之後，請改用 NSURLSessionConfiguration.

NSURLSessionConfiguration

session with basic set of properties that control various policies on a sessionwide basis. These properties are set on a session at the time of its creation and cannot be changed later. If you need to change these policy properties, create a new session with a modified session configuration.

sharedSession

Returns a shared singleton session object.

Please review Apple Documents first as these are the source of very information.

所以，每次都去 create new session 可以避免某些問題！

使用 proxy 的範例如下：

It turns out, the dictionary keys you want are the Stream variants, they are the ones that resolve down to “HTTPProxy” and such:

NSString* proxyHost = @"myProxyHost.com";
NSNumber* proxyPort = [NSNumber numberWithInt: 12345];

// Create an NSURLSessionConfiguration that uses the proxy
NSDictionary *proxyDict = @{
    @"HTTPEnable"  : [NSNumber numberWithInt:1],
    (NSString *)kCFStreamPropertyHTTPProxyHost  : proxyHost,
    (NSString *)kCFStreamPropertyHTTPProxyPort  : proxyPort,

    @"HTTPSEnable" : [NSNumber numberWithInt:1],
    (NSString *)kCFStreamPropertyHTTPSProxyHost : proxyHost,
    (NSString *)kCFStreamPropertyHTTPSProxyPort : proxyPort,
};

NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration ephemeralSessionConfiguration];
configuration.connectionProxyDictionary = proxyDict;

// Create a NSURLSession with our proxy aware configuration
NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:[NSOperationQueue mainQueue]];

// Form the request
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"https://www.google.com?2"]];

// Dispatch the request on our custom configured session
NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:
                              ^(NSData *data, NSURLResponse *response, NSError *error) {
                                  NSLog(@"NSURLSession got the response [%@]", response);
                                  NSLog(@"NSURLSession got the data [%@]", data);
                              }];

NSLog(@"Lets fire up the task!");
[task resume];

如果直接使用上面的 code 可能會遇到這一個 warning:

Sending 'ViewController *const __strong' to parameter of incompatible type 'id<NSURLSessionDelegate> _Nullable'

解法：

Confirm <NSURLSessionDelegate> in your header file and it will solve the issue i think,

  @interface ViewController : UIViewController <NSURLSessionDataDelegate>

It is because you are setting delegate to self in NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil]; So it’s requires to confirm NSURLSessionDataDelegate protocol.