在主窗口上创建新的UIWindow

问题描述

在我的应用程序中，我想在主UIWindow上创建一个新的 UIWindow ，我写了如下，但它不起作用。
首先，我创建一个 UIWindow 作为主窗口，然后使其成为键和可见，然后创建一个新的 UIWindow overlay，但没有任何反应。

In my app I want to create a new UIWindow over the main UIWindow, And I wrote as following, but it don't works.first, i create a UIWindow as the main window, and then make it key and visible, and then create a new UIWindow overlay, but nothing happens.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    self.window.backgroundColor = [UIColor redColor];
    ViewController *vc = [[ViewController alloc]initWithNibName:@"ViewController" bundle:nil];
    self.window.rootViewController = vc;
    [self.window makeKeyAndVisible];
    UIWindow *window1 = [[UIWindow alloc] initWithFrame:CGRectMake(0, 0, 320, 320)];
    window1.backgroundColor = [UIColor redColor];
    window1.windowLevel = UIWindowLevelAlert;
    [window1 makeKeyAndVisible];
    return YES;
}

推荐答案

 UIWindow *window1 = [[UIWindow alloc] initWithFrame:CGRectMake(0, 0, 320, 320)];
window1.backgroundColor = [UIColor redColor];
window1.windowLevel = UIWindowLevelAlert;
[window1 makeKeyAndVisible];

最后我知道为什么它不起作用，因为window1是一个方法var，它会丢失方法执行后。所以我为它声明了一个新的@property，因为

Finally I know why it doesn't work, because window1 is a method var, and it will lost after the method executed. So I declare a new @property for it, as

@property (strong, nonatomic) UIWindow *window2;

和
更改代码如

andchange the code like

 UIWindow *window2 = [[UIWindow alloc] initWithFrame:CGRectMake(0, 80, 320, 320)];
window2.backgroundColor = [UIColor redColor];
window2.windowLevel = UIWindowLevelAlert;
self.window2 = window2;
[window2 makeKeyAndVisible];

它有效！

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