To animate (fade) text change in UILabel (SWIFT)

gistfile1.swift

The proper way to fade a UILabel (or any UIView for that matter) is to use a Core Animation Transition. This will not flicker, nor will it fade to black if the content is unchanged.

A portable and clean solution is to use a Extension in Swift (invoke prior changing visible elements)

// Usage: insert view.fadeTransition right before changing content
extension UIView {
    func fadeTransition(duration:CFTimeInterval) {
        let animation:CATransition = CATransition()
        animation.timingFunction = CAMediaTimingFunction(name:
            kCAMediaTimingFunctionEaseInEaseOut)
        animation.type = kCATransitionFade
        animation.duration = duration
        self.layer.addAnimation(animation, forKey: kCATransitionFade)
    }
}
Invocation looks like this:

// This will fade
aLabel.fadeTransition(0.4)
aLabel.text = xxx

Hola.

I tidied this up for XCode 10 (yea, I know) specifically for UILabel use, but it's still not working for me:

extension UILabel {
    func fadeTransition(duration: CFTimeInterval) {
        let animation: CATransition = CATransition()
        animation.timingFunction = CAMediaTimingFunction(name: CAMediaTimingFunctionName.easeInEaseOut)
        animation.type = CATransitionType.fade
        animation.duration = duration
        self.layer.add(animation, forKey: CATransitionType.fade.rawValue)
    }

This however did work:

UILabel.animate(withDuration: 0.5,
                delay       : 1.0,
                options     : [.repeat, .autoreverse, .curveEaseOut],
                animations  : { textLabel.alpha = 0.0 }) { (finished) in textLabel.alpha = 1.0 }