I'm swizzling willMoveToWindow: and I came across an issue where it was being called twice on views.
When a new view controller is pushed onto a UINavigationController,
willMoveToWindow: is called on the existing view with nil value (Makes sense since the view is moving offscreen)
After that time, the method willMoveToWindow: is called again , but now with with the original window.
My initial thought is that swizzling and calling the window property before the original method has kicked in.
To be on the safe side I've created a small sample project and confirmed the the same behavior.
Basically I need a way to know for sure that the view is not on the window (Because I am triggering logic when a view is moving to window which in reality shouldn't be run (at least not twice))
For reference the problem can be reproduced with the following code:
@implementation RandomView
-(void)willMoveToWindow:(UIWindow *)newWindow {
// when the new view controller is pushed -
//the method is called twice on the existing view (on the screen view)-
//first time will be called with nil -
//second time with the original window
NSLog(@"********%s <RandomView %p> <Window %p>",__PRETTY_FUNCTION__,self,newWindow);
}
-(void)didMoveToWindow {
NSLog(@"********%s <RandomView %p> <Window %p>",__PRETTY_FUNCTION__,self,self.window);
}
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
RandomView *k = [[RandomView alloc] initWithFrame:self.view.bounds];
[self.view addSubview:k];
}
-(void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
ViewController *vc = [[ViewController alloc] init];
[self.navigationController pushViewController:vc animated:YES];
});
});
//[self becomeFirstResponder];
}
@end
EDIT Console
[RandomView willMoveToWindow:] <RandomView 0x7f8b21e16630> <Window 0x7f8b21d220d0>
[RandomView didMoveToWindow] <RandomView 0x7f8b21e16630> <Window 0x7f8b21d220d0>
//THIS IS THE ISSUE
[RandomView willMoveToWindow:] <RandomView 0x7f8b21e16630> <Window 0x0>
[RandomView didMoveToWindow] <RandomView 0x7f8b21e16630> <Window 0x0>
[RandomView willMoveToWindow:] <RandomView 0x7f8b21e16630> <Window 0x7f8b21d220d0>
[RandomView didMoveToWindow] <RandomView 0x7f8b21e16630> <Window 0x7f8b21d220d0>
[RandomView willMoveToWindow:] <RandomView 0x7f8b21e16630> <Window 0x0>
[RandomView didMoveToWindow] <RandomView 0x7f8b21e16630> <Window 0x0>
view.window? Why do you need to swizzle? Swizzling is bad. – Amuck