On iOS, double-click Home to switch

On iOS, double-click Home to switch

If you double-click Home, you will be taken to the iOS App's switcher page, where the App suspended by the current system is listed. The screen-cutting of each App is displayed. I believe everyone is familiar with this stuff. It is actually the last screen load of each App before it is suspended.

So how can we customize the display on App Switcher and understand that it is actually a screen loading for the App, so when it enters the background, we will change its appearance, will the uploaded image be changed?

After understanding this principle, let's give it a try.

A new project, three pictures, defautl.png, Defautl@2x.png, Default-568h@2x.png, put it into the project.

We declare a UIImageView variable in AppDelegate. h.

The Code is as follows:

-(Void) applicationWillResignActive :( UIApplication *) application {if (! ScreenShotView) {screenShotView = [[UIImageView alloc] initWithFrame: [self. window frame]; [screenShotView setImage: [UIImage imageNamed: @ "Default-568h"]; [self. window addSubview: screenShotView];} screenShotView. alpha = 1 ;}- (void) applicationDidBecomeActive :( UIApplication *) application {screenShotView. alpha = 0 ;}