iOS自带的毛玻璃的效果

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    
    
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // Override point for customization after application launch.
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];
    
    UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:self.window.bounds];
    UIVisualEffectView *view = [[UIVisualEffectView alloc] initWithEffect:[UIBlurEffect effectWithStyle:UIBlurEffectStyleDark]];
    view.frame = CGRectMake(0, 0, 375, 500);
    [scrollView addSubview:view];
    scrollView.contentOffset = CGPointMake(0, 500);
    scrollView.contentSize = CGSizeMake(375, 10000);
    [self.window addSubview:scrollView];
    
    return YES;
}