在主窗口上创建新的UIWindow

Question

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，然后使其键和可见，然后创建一个新的UIWindow叠加，但没有任何反应。

- (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;
}

Answer 1

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

最后我知道它为什么不起作用，因为window1是一个方法var，它会在方法执行后丢失。所以我宣布一个新的@property，因为

@property (strong, nonatomic) UIWindow *window2;

并改变代码

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

有用！

Answer 2

Xcode 8 + Swift

class ViewController: UIViewController {
    var coveringWindow: UIWindow?

    func coverEverything() {
        coveringWindow = UIWindow(frame: (view.window?.frame)!)

        if let coveringWindow = coveringWindow {
            coveringWindow.windowLevel = UIWindowLevelAlert + 1
            coveringWindow.isHidden = false
        }
    }
}

根据the documentation，要接收没有相关坐标值的事件，例如键盘输入，请将其设为key，而不仅仅是! isHidden：

coveringWindow.makeKeyAndVisible()

您甚至可以控制其背景的透明度，以获得烟雾效果：

coveringWindow.backgroundColor = UIColor(white: 0, alpha: 0.5)

请注意，此类窗口需要处理方向更改。

Answer 3

你的window1对象是一个局部变量，当代码用完这个方法时，这个对象就不再存在了。我们创建的任何UIWindow对象都将添加到[[UIApplication sharedApplication] windows]，但是这个数组只保留一周引用任何UIWindow对象，所以由你自己的代码来保持窗口对象存在。为什么苹果这样实现，我想，是[UIApplication sharedApplication]只要应用程序运行，对象就会存在，这样做是为了避免保留UIWindow对象，这些对象只需要存在一段时间才能永远存在于内存中。

更重要的是，您的代码可以与MRC一起运行。

Answer 4

斯威夫特4

为了避免内存泄漏，我更喜欢以这种方式初始化我的自定义窗口，如Apple提出的：

如果要为应用程序提供自定义窗口，则必须实现此属性的getter方法，并使用它来创建并返回自定义窗口。

例：

var myCustomWindow: UIWindow? = CustomWindow(frame: UIScreen.main.bounds)

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

    let mainController: MainViewController = UIStoryboard(name: "Main", bundle: nil).instantiateInitialViewController() as! MainViewController
    self.myCustomWindow?.rootViewController = mainController
    self.myCustomWindow?.makeKeyAndVisible()
}

Answer 5

尝试在mainWindow上添加一个UIView而不是另一个UIWindow ...

- (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];
    UIView * viewAlert = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 320)];
    viewAlert.backgroundColor = [UIColor redColor];
    [self.window.rootViewController.view addSubView:viewAlert];
    /* or you can use following..
    [self.window addSubView:viewAlert];
    */
    [viewAlert release]; //FOR NON ARC
    return YES;
}

Answer 6

在迅速，新的UIWindow可以添加如下..

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?
    var viewController: ViewController?
    var navigationController: UINavigationController?

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
        self.viewController = ViewController(nibName: "ViewController", bundle:NSBundle.mainBundle())
        self.navigationController = UINavigationController(rootViewController: self.viewController!)
        self.window!.rootViewController = self.navigationController
        //  self.window!.addSubview(self.viewController!.view)
        self.window!.makeKeyAndVisible()
        return true
    }

    //Other methods..
}