Toggle Slow Animations

iOS Simulator has a feature that slows animations, you can toggle it either by pressing ⌘T or choosing Debug > Toggle Slow Animations in Frontmost App. It’s very useful, but what if we want to do the same on device? It’s easy, fast and simple.

CALayer has a property called speed, which is a time multiplier. This means that if we have an animation with a duration of 1 second, and set the layer’s speed to 2, it’ll take just 0.5 seconds to finish. The best thing about it is that it’s related to the parent layer. So when we change the speed of a particular CALayer, every child layer will be affected. So, if we change UIWindow layer speed, every CALayer in our application will perform animations with that custom speed value. That leaves us with this two extensions:

extension UIWindow {

    var slowAnimationsEnabled: Bool {
        get {
            return layer.speed != 1
        }
        set {
            layer.speed = newValue ? 0.2 : 1
        }
    }
}

extension UIApplication {

    func setSlowAnimationsEnabled(enabled: Bool) {
        windows.map({ window in (window as? UIWindow)?.slowAnimationsEnabled = enabled })
    }
}

And you can call it in both ways:

UIApplication.sharedApplication().keyWindow?.slowAnimationsEnabled = true
UIApplication.sharedApplication().setSlowAnimationsEnabled(true)

You can go further and expose this to your testers, through iOS Settings Bundle or a fancy shake gesture. Pretty handy!