On Mon, Nov 26, 2012, at 10:46 AM, Matt Neuburg wrote: > I have noticed by experimentation that if I have a layout constraint on a > view that sets its height at (say) 36, I can later change the view's > frame in code to set its height at (say) 50. The view's height does > visibly change, but logging proves that the layout constraint does not > change. > > (1) How can this be? The view would appear to be violating its own layout > constraint.
Constraints don't care about the view's frame. They only care about each other. When the constraint system runs, it calls -setFrame: on the views. It never pays attention to what values they have. > (2) More important: Is this a bad situation? In other words, once I've > decided to use layout constraints at all, must I then use them for > everything and avoid frame/bounds? Can something bad happen later because > of this conflict? Yes, this is a bad situation. You should use constraints. You run the risk of your views being resized whenever the next layout pass is triggered. Additionally, my statement above is a lie: constraints don't care about the current frame of your views, but if a view is set to translate its autoresizing mask into constraints, and either the X or Y dimension is not fully stretchable, it updates these constraints' constants with the values from the frame whenever the frame changes size. So that means you CAN cause a conflict by calling -setFrameSize: on a view if you're still mixing constraints with autoresizing-mask-based layout. --Kyle Sluder _______________________________________________ Cocoa-dev mailing list ([email protected]) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [email protected]
