1: The system crashes immediately after the upgrade

An error

 **Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'App called -statusBar or -statusBarWindow on UIApplication: this code must be changed as there's no longer a status bar or status bar window. Use the statusBarManager object on the window scene instead.'* *Copy the code

StatusBar or statusBarWindowiOS 13 is disabled on uiApplication. Cause: There is a call in the system

 UIView *statusBar = [[[UIApplication sharedApplication] valueForKey:@"statusBarWindow"] valueForKey:@"statusBar"];
 statusBar.backgroundColor = [UIColor clearColor];
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Just take that out.

2: Running found usepresentViewControllerThe style of the calls has changed.

Here are some details of what’s been updated in iOS13. The one you see is called a Sheet popover

UIViewController 

typedef NS_ENUM(NSInteger, UIModalPresentationStyle) { UIModalPresentationFullScreen = 0, UIModalPresentationPageSheet API_AVAILABLE (ios (3.2)) API_UNAVAILABLE (tvos), UIModalPresentationFormSheet API_AVAILABLE (ios (3.2)) API_UNAVAILABLE (tvos), UIModalPresentationCurrentContext API_AVAILABLE (ios (3.2)), UIModalPresentationCustom API_AVAILABLE (ios (7.0)), UIModalPresentationOverFullScreen API_AVAILABLE (ios (8.0)), UIModalPresentationOverCurrentContext API_AVAILABLE (ios (8.0)), UIModalPresentationPopover API_AVAILABLE (ios (8.0)) API_UNAVAILABLE (tvos), UIModalPresentationBlurOverFullScreen API_AVAILABLE (tvos (11.0)) API_UNAVAILABLE (ios) API_UNAVAILABLE (watchos), UIModalPresentationNone API_AVAILABLE (ios (7.0)) = 1, UIModalPresentationAutomatic API_AVAILABLE (ios) (13.0) = 2,};Copy the code

Manually set the jump controller to full screen

  UINavigationController  *nav = [[UINavigationController alloc] initWithRootViewController:controller];
 nav.modalPresentationStyle = UIModalPresentationFullScreen;
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3: Use textField extension method to flash back

Error message

** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UITextView placeholderLabel]: unrecognized selector sent to instance 0x7fcfbd8ad000'
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The root cause is that ios13 does not allow properties to be modified using KVO. Used in the code

 color = [textField valueForKeyPath:@"_placeholderLabel.textColor"];

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4: An error is reported using Xcode11 packaging

error: Multiple commands produce ****:
1) Target '* * *' (project '* * *') has copy command from ***'
2) That command depends on command in Target '* * *' (project '* * *'): script phase "[CP] Copy Pods Resources"Copy the code

This is because local files are duplicated. The reason is a bug in Xcode before Xcode11. The bundle file also needs to be manually imported externally when a Pod is imported. Xcode11 fixes this problem so that there are two bundles. If Xcode is not updated, you can configure File ->WorkSpace Settings… Set up the