Question

I am getting the following message from Cocoa Auto Layout mechanism:

Set the NSUserDefault NSConstraintBasedLayoutVisualizeMutuallyExclusiveConstraints to YES to have -[NSWindow visualizeConstraints:] automatically called when this happens.

But I don’t know how to “Set the NSUserDefault NSConstraintBasedLayoutVisualizeMutuallyExclusiveConstraints to YES”.

How do I set this?

Answer 1

You may also set

Objective C:

[[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"NSConstraintBasedLayoutVisualizeMutuallyExclusiveConstraints"];

Swift <3:

NSUserDefaults.standardUserDefaults().setBool(true, forKey: "NSConstraintBasedLayoutVisualizeMutuallyExclusiveConstraints")

Swift 3-4.2 (at least):

UserDefaults.standard.set(true, forKey: "NSConstraintBasedLayoutVisualizeMutuallyExclusiveConstraints")

in applicationDidFinishLaunching.

Note that this will set it for both yourself and your end-users, which may not be what you want (don’t go into production like this!). You can set it only for yourself by setting the -NSConstraintBasedLayoutVisualizeMutuallyExclusiveConstraints YES argument in your "Debug" run scheme (described in a separate answer).