Toggle slow animation while debugging with iOS Device

In Swift 3:

UIApplication.shared.windows.first?.layer.speed = 0.1

Or, if you're anywhere in your AppDelegate and you only use one window, you can do this:

window?.layer.speed = 0.1

It's not possible in exactly the same way as with the Simulator, but there is a good way to accomplish the same effect using lldb.

Use the debugger to pause code execution, and then enter the command:

p [(CALayer *)[[[[UIApplication sharedApplication] windows] objectAtIndex:0] layer] setSpeed:.1f]

into the debugger.

Thanks to this link for the solution.