added subview won't show after the app relaunch - iphone

Question

I have a subview added on app relaunch, on the applicationDidBecomeActive got called, but it's not shown, what could be the reason?
- (UIView *)mySubView {
if (_mySubView == nil) {
_mySubView = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
_mySubView.opaque = NO;
_mySubView.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.5f];
_mySubView.exclusiveTouch = YES;
[_mySubView setUserInteractionEnabled:NO];
}
return _mySubView;
}
- (void)applicationDidBecomeActive:(UIApplication *)application {
UIWindow *window = [[[UIApplication sharedApplication] windows] objectAtIndex:0];
[window addSubview:[self mySubView]];
}
What's more interesting is that - it'll shown if I leave the app launched, turn off the device, then turn the device back on. But if I close the app, then relaunch it, I won't be able to see the subview.

Answer 1

Please add the following line like this,
- (void)applicationDidBecomeActive:(UIApplication *)application
{
UIWindow *window = [[[UIApplication sharedApplication] windows] objectAtIndex:0];
[window addSubview:[self mySubView]];
[window makeKeyAndVisible];
}
and also change the color [UIColor blueColor];
You will see the effect sure
Enjoy!

Answer 2

IF you're on your App delegate and you have a window property, as you should have, you could just simply do this:
[[self window] addSubview:[self mySubView]];
For setting the window property do this:
In your AppDelegate.h
#property (strong, nonatomic) UIWindow *window;
In your AppDelegate.m - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
.
.
.
//Create your main controller
.
.
.
[self.window setRootViewController:mainController];
[self.window makeKeyAndVisible];