UIApplicationDidBecomeActiveNotification and setRightBarButtonItem:animated: - ios

Question

TL;DR Update: Basically what I need is to delay my code until iOS finishes its "app startup" animation.
I would like to animate content of a navigation bar when my app becomes active. In my controller, I'm subscribed to UIApplicationDidBecomeActiveNotification and use setRightBarButtonItem:animated: to perform the change.
The problem is that the change is not animated.
I did some experimentation and discovered that if I wait a little ([NSThread sleepForTimeInterval:.3]), it's animating without any issues.
Here is a simple view controller demonstrating the problem:
#interface TESTViewController ()
#property (strong, nonatomic) IBOutlet UINavigationBar *navigationBar;
#end
#implementation TESTViewController
- (void)viewDidLoad
{
[super viewDidLoad];
UINavigationItem *item = [UINavigationItem new];
UIBarButtonItem *oldItem = [[UIBarButtonItem alloc] initWithTitle:#"Old" style:UIBarButtonItemStyleBordered target:nil action:NULL];
[item setRightBarButtonItem:oldItem];
[[self navigationBar] setItems:#[item] animated:NO];
}
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(applicationDidBecomeActiveNotificationAction:) name:UIApplicationDidBecomeActiveNotification object:nil];
}
- (void)applicationDidBecomeActiveNotificationAction:(NSNotification *)notification
{
// [NSThread sleepForTimeInterval:.3];
UIBarButtonItem *newItem = [[UIBarButtonItem alloc] initWithTitle:#"New" style:UIBarButtonItemStyleBordered target:nil action:NULL];
[[[self navigationBar] items][0] setRightBarButtonItem:newItem animated:YES];
}
#end
I'd like find a better solution than blocking the thread or performing the change after a fixed delay.

Answer 1

Simply use dispatch_after on the main queue instead of calling
+[NSThread sleepForTimeInterval:] class method.
Pass your animation as a block and it should work perfectly.

Answer 2

When posting notifications, I don't use your methods.
I use:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(changeButton) name:#"changeButton" object:nil];
on the receiving end.
And on the posting end, I call
[[NSNotificationCenter defaultCenter] postNotificationName:#"changeButton" object:nil];
Try moving your code to the method:
-(void)changeButton{
UIBarButtonItem *newItem = [[UIBarButtonItem alloc] initWithTitle:#"New" style:UIBarButtonItemStyleBordered target:nil action:NULL];
[[[self navigationBar] items][0] setRightBarButtonItem:newItem animated:YES];
}
Hope this helps!

Answer 3

Have you tried to performSelectorAfterDelay?
Try something like this:
- (void)applicationDidBecomeActiveNotificationAction:(NSNotification *)notification{
[self performSelector:#selector(yourAnimationAction) withObject:nil afterDelay:1];
}
- (void)yourAnimationAction{
//Set your NavAnimation here
[self.navigationItem setRightBarButtonItem:theItem animated:TRUE];
}
Just change the Delay to fit your apps wakeup delay... maybe this will take the effect?

Answer 4

Try by moving
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(applicationDidBecomeActiveNotificationAction:) name:UIApplicationDidBecomeActiveNotification object:nil]; to viewDidLoad: method. I think object is not registered for "UIApplicationDidBecomeActiveNotification" while it is fired.

Answer 5

Just call viewDidAppear: manually from within your applicationDidBecomeActiveNotificationAction: method. Place your animation code in the viewDidAppear: method. Hope this helps.