Update UIProgressView from NSProgress

I have this observer and I am trying to update my UIProgressView in this way: ``` - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context { NSProgress *progress = object; NSLog(@"PROG: %f", progress.fractionCompleted); [progressBar setProgress:_progressReceive.fractionCompleted animated:YES]; // Check which KVO key change has fired if ([keyPath isEqualToString:kProgressCancelledKeyPath]) { // Notify the delegate that the progress was cancelled [progressBar removeFromSuperview]; NSLog(@"CANCEL"); } else if ([keyPath isEqualToString:kProgressCompletedUnitCountKeyPath]) { // Notify the delegate of our progress change if (progress.completedUnitCount == progress.totalUnitCount) { // Progress completed, notify delegate NSLog(@"COMPLETE"); [progressBar removeFromSuperview]; } } } ``` The NSLog is displaying data: ``` ... 2013-10-29 19:55:26.831 Cleverly[2816:6103] PROG: 0.243300 2013-10-29 19:55:26.835 Cleverly[2816:6103] PROG: 0.243340 2013-10-29 19:55:26.838 Cleverly[2816:6103] PROG: 0.243430 ... ``` But the progressBar is not updating. I notice that if I use an NSTimer instead it does update: ``` -(void)progressSend:(NSTimer*)timer{ NSLog(@"Fraction Complete: %@", [NSNumber numberWithDouble:progressSend.fractionCompleted]); [progressBar setProgress:progressSend.fractionCompleted animated:YES]; } ``` Why is this??