Problems with iOS 6 and UIActivityIndicator in a UINavigationBar titleView - ios6

Question

been having problems with this since iOS 6. I can't really figure out whats changed that would cause this behavior. This used to work perfectly in 5. Now the activity indicator doesn't come up timely or at all. Any help would be much appreciated.
-(void)myMethod
{
UIView *currentTitleView = [[self navigationItem] titleView];
// Create an activity indicator and start it spinning in the nav bar
UIActivityIndicatorView *aiview = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];
[[self navigationItem] setTitleView:aiview];
[aiview startAnimating];
// Start of Block code
void (^block)(arg1, arg2) =
^(arg1, arg2)
{
block code;
[aiview stopAnimating];
[[self navigationItem] setTitleView:currentTitleView];
};
// End of Block code
}

Answer 1

It sounds like myMethod is being called from a background thread. As a general rule, all interactions with UIKit elements (which includes UIActivityIndicatorView) should always be done on the main thread. Try using GCD to move the UI code to the main queue (a.k.a. main thread).
-(void)myMethod {
dispatch_async(dispatch_get_main_queue(), ^{
UIView *currentTitleView = [[self navigationItem] titleView];
// Create an activity indicator and start it spinning in the nav bar
UIActivityIndicatorView *aiview = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];
[[self navigationItem] setTitleView:aiview];
[aiview startAnimating];
});
// Start of Block code
void (^block)(arg1, arg2) =
^(arg1, arg2)
{
block code;
dispatch_async(dispatch_get_main_queue(), ^{
[aiview stopAnimating];
[[self navigationItem] setTitleView:currentTitleView];
});
};
// End of Block code
}