Question

I have started a new iOS “Empty Application“-template project. When I put this code inside of the application:didFinishLaunchingWithOptions: method, it works fine:

 CGRect frame = CGRectMake(10, 10, 300, 25);
 UILabel *helloLabel = [UILabel new];
 [helloLabel setFrame:frame];
 helloLabel.text = @"Hello iPhone!";  
 [self.window addSubview:helloLabel];

But what I really want to do is make an “addHello” class method in another class, so that what shows up in application:didFinishLaunchingWithOptions: is just:

[MyOtherClass addHello];

This is what I’ve tried putting in the other class:

+ (void) addHello { 

CGRect frame = CGRectMake(10, 10, 300, 25);
UILabel *helloLabel = [UILabel new];
[helloLabel setFrame:frame];
helloLabel.text = @"Hello iPhone!";

UIWindow *window = [[UIApplication sharedApplication] keyWindow];
[window addSubview:helloLabel];

}

But that doesn’t work. What am I supposed to do?

Answer 1

My guess would be that [[UIApplication sharedApplication] keyWindow] is coming back nil in your code because you are calling your addHello method before the UIWindow’s makeKeyAndVisible method has not been called. I wonder if this would work:

In your appDidFinishLaunching method:

[MyOtherClass addHelloWithWindow:self.window];

and then your MyOtherClass

+ (void) addHelloWithWindow:(UIWindow *)window
{ 
    CGRect frame = CGRectMake(10, 10, 300, 25);
    UILabel *helloLabel = [UILabel new];
    [helloLabel setFrame:frame];
    helloLabel.text = @"Hello iPhone!";
    [window addSubview:helloLabel];
}