Fade UIBarButtonItem When Swapped - ios

Question

When I change my UIBarButtonItems they change abruptly, unlike the default which gives a nice but speedy fade animation. You can see this when segueing between view controllers, for instance, the back button will fade in and out. How can I simulate the same effect?

Answer 1

Update - Based on this answer - https://stackoverflow.com/a/10939684/2649021
It looks like you would have to do something like this to make the button itself fade out.
[self.navigationItem setRightBarButtonItem:nil animated:YES];
And do something like this to make it fade in
[self.navigationItem setRightBarButtonItem:myButton animated:YES];
Otherwise if you want more control over animation properties you would have to create a custom view I believe.
EDIT: I just confirmed that you can fade a UIBarButtonItem custom view using this.
As a test I created a simple project and dropped a UIBarButtonItem onto the navigation bar. I created an outlet to the view controller. In viewDidLoad on the view controller I setup a custom view
-(void)viewDidLoad{
[super viewDidLoad];
UILabel *lbl = [[UILabel alloc]initWithFrame:CGRectMake(0,0,40,40)];
lbl.text = #"test";
UIView *customView = [[UIView alloc]initWithFrame:CGRectMake(0,0,40,40)];
[customView addSubview:lbl];
self.barButtonItem.customView = customView;
}
As a test in viewDidAppear I animated it
-(void)viewDidAppear:(BOOL)animated
{
[UIView animateWithDuration:3.0
delay:3.0
options:UIViewAnimationOptionCurveEaseOut
animations:^{
self.barButtonItem.customView.alpha = 0;
}
completion:^(BOOL finished) {
NSLog(#"animation complete");
}];
EDIT: Here's a link to Apples Documentation for a full explanation of UIView animations.
https://developer.apple.com/library/ios/documentation/windowsviews/conceptual/viewpg_iphoneos/animatingviews/animatingviews.html

Answer 2

You might have to create a custom bar button item using a view or an image, and then animate the properties of the view as digitalHound shows.