Open Radar

 
29-Aug-2013 06:38 PM James Savage:
SUMMARY:
With iOS 7 the format of the UIProgressView control changed for the UIProgressViewStyleBar style. In this new style Apple recommends placing the progress view at the bottom of a navigation bar or top of a toolbar, as seen in Messages, Mail, and Safari.

However, UIKit does not expose a readily available method to achieve this style. The only ways I have found involve manually adding the UIProgressView to the bar, managing its frame manually (as attempting to add NSLayoutConstraints to a bar managed by a UINavigationController will result in an exception[1]), and managing the removal, and associated animations, or a navigation controller's back and interactive back transitions.

Overall this is a rather large body of work for 3rd party developers to duplicate just to achieve the recommend appearance for a progress view in a bar, and it would be very nice if a simple interface were exposed to make this easier and standardized through the system.

[1]: *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Cannot modify constraints for UINavigationBar managed by a controller'

REGRESSION:
Prior to iOS 7, developers could get away with adding a progress view as an item to a toolbar or the titleView of navigation bar, however, in order to span the full width of the bar and not interfere with other items, this strategy no longer works.