ARAnnotatedSliderView.m

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
	UIImageView *thumbImageView = (UIImageView *)context;
	
	if ([keyPath isEqualToString:kARPageScrubberViewKeypathFrame]) {
		self.bubbleView.pageNumber = self.pageIndex + 1;
		CGRect bubbleViewFrame = self.bubbleView.frame;
		bubbleViewFrame.origin.x = thumbImageView.frame.origin.x - round(bubbleViewFrame.size.width / 2) + _slider.frame.origin.x + round(thumbImageView.frame.size.width / 2);
		bubbleViewFrame.origin.y = thumbImageView.frame.origin.y - bubbleViewFrame.size.height;
		self.bubbleView.frame = bubbleViewFrame;
		if (self.bubbleView.hidden && _slider.tracking) {
			[self.bubbleView show:YES];
		}
	} else if ([keyPath isEqualToString:kARPageScrubberViewKeypathTracking]) {
		if (_slider.tracking) {
			if (self.bubbleView.hidden) {
				[self.bubbleView show:YES];
			}
			return;
		} else {
			[_slider setValue:self.pageIndex animated:YES];
		}
		
		if (nil != _bubbleTimer) {
			[_bubbleTimer invalidate];
			[_bubbleTimer release]; _bubbleTimer = nil;
		}
		
		_bubbleTimer = [[NSTimer alloc] initWithFireDate:[NSDate dateWithTimeIntervalSinceNow:0.25f] interval:0.0f target:self.bubbleView selector:@selector(hide) userInfo:nil repeats:NO];
		[[NSRunLoop currentRunLoop] addTimer:_bubbleTimer forMode:NSDefaultRunLoopMode];
	}
}