Second UIWindow Not Displaying (iPad) - cocoa-touch

Question

I am attempting to create two UIWindows because I would like two UINavigationControllers on screen at the same time on my app. I initialize two windows in my app delegate but only one window's view is displayed. Does anyone know why this is so?
Here is the code I used:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
UIViewController * controller1 = [[UIViewController alloc] init];
[controller1.view setBackgroundColor:[UIColor grayColor]];
UINavigationController * nav1 = [[UINavigationController alloc] initWithRootViewController:controller1];
[window addSubview:nav1.view];
[window makeKeyAndVisible];
UIWindow * window2 = [[UIWindow alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
UIViewController * controller2 = [[UIViewController alloc] init];
[controller2.view setBackgroundColor:[UIColor yellowColor]];
UINavigationController * nav2 = [[UINavigationController alloc] initWithRootViewController:controller2];
[window2 addSubview:nav2.view];
[window2 makeKeyAndVisible];
NSLog(#"%#", [[UIApplication sharedApplication] windows]);
return YES;
}
The gray from the first window is visible, but the yellow from the second is not. The output from this is:
"<UIWindow: 0x591e650; frame = (0 0; 768 1024); opaque = NO; autoresize = RM+BM; layer = <CALayer: 0x591e7a0>>",
"<UIWindow: 0x5923920; frame = (0 0; 100 100); layer = <CALayer: 0x59239a0>>"
which means the second window is created and added to the application, but just not displayed. Does anyone know why this is so?
Thanks in advance!

Answer 1

The two UIWindow's windowLevel property is equal, they are all UIWindowLevelNormal.
If you want the second UIWindow display font of the first UIWindow, You should set the second UIWindow's windowLevel value bigger. Like:
window2.windowLevel = UIWindowLevelNormal + 1;
PS:
[window makeKeyAndVisible];
...
[window2 makeKeyAndVisible];
There is only one keyWindow at a time, The key window is the one that is designated to receive keyboard and other non-touch related events. Only one window at a time may be the key window.

Answer 2

Just use a UISplitViewController.
Or try MGSplitVIewController if you need to customization. It might have what you need.

Answer 3

I've discovered how to get the second UIWindow to display. You must set the clipsToBound property to YES. Otherwise, the view from one of the windows will completely cover the other view. The two windows were properly added and visible after all.

Answer 4

This might be a really old post but I just run into the same problem. Some coding mistakes where already answered but the main issue we have here is how you instantiating the UIWindow.
Here is a Swift example how to display another UIWindow correctly.
#UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow? = UIWindow(frame: UIScreen.mainScreen().bounds)
let newWindow = UIWindow(frame: UIScreen.mainScreen().bounds)
// save a reference to your Window so it won't be released by ARC
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
self.window!.rootViewController = SomeViewController()
self.window!.makeKeyAndVisible()
// in your example you have created the window inside this method,
// which executes correctly and at the end of this method just releases the window,
// because you never saved the reference to the window
self.newWindow.rootViewController = SomeOtherViewController()
self.newWindow.windowLevel = UIWindowLevelStatusBar + 1.0
self.newWindow.hidden = false
return true
}
}
Btw. you don't have to create a UIWindow in AppDelegate. It depends on your code behavior.

Answer 5

try this code...
id delegate = [[UIApplication sharedApplication] delegate];
[[delegate FirstView] presentModalViewController:SecondView animated:YES];