iOS开发实现支付宝双击Home键进入后台后的毛玻璃效果

为了保护用户的隐私（其实并没有什么卵用）支付宝加入了后台毛玻璃效果，怎么实现呢，其实很简单，只需要在appDelegate中写几行代码即可，为了显示不那么的突兀，最好加上动画过渡一下。

#import "AppDelegate.h"

@interface AppDelegate ()

@property (nonatomic, strong, nullable) UIVisualEffectView *visualEffectView;

@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    
    return YES;
}

- (void)applicationWillResignActive:(UIApplication *)application {
    UIBlurEffect *blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];
    self.visualEffectView = [[UIVisualEffectView alloc] initWithEffect:blurEffect];
    self.visualEffectView.alpha = 0;
    self.visualEffectView.frame = self.window.frame;
    [self.window addSubview:self.visualEffectView];
    [UIView animateWithDuration:0.5 animations:^{
        self.visualEffectView.alpha = 1;
    }];
}

- (void)applicationDidEnterBackground:(UIApplication *)application {
    
}

- (void)applicationWillEnterForeground:(UIApplication *)application {
    
}

- (void)applicationDidBecomeActive:(UIApplication *)application {
    [UIView animateWithDuration:0.5 animations:^{
        self.visualEffectView.alpha = 0;
    } completion:^(BOOL finished) {
        [self.visualEffectView removeFromSuperview];
    }];
}

- (void)applicationWillTerminate:(UIApplication *)application {
    
}

@end