Set AutoLayout Size Class Programmatically?

Question

With iOS 8 and Xcode 6, in storyboards we now have the screen size grid letting us select a size class. Where you can select layout formatting for the different screen sizes

Answer 1

iOS 8 introduces the active property on NSLayoutConstraint. It allows you to activate or deactivate a constraint. There are also methods to activate/deactivate multiple constraints.

+ (void)activateConstraints:(NSArray *)constraints
+ (void)deactivateConstraints:(NSArray *)constraints

• Keep your constraints in arrays when creating them programmatically.
• Create an array for each of the layouts you need.
• Activate/Deactivate whatever set of constraints you need from within willTransitionToTraitCollection