Animate text change in UILabel

I wonder if it works, and it works perfectly!

Objective-C

[UIView transitionWithView:self.label                   duration:0.25f                    options:UIViewAnimationOptionTransitionCrossDissolve                 animations:^{    self.label.text = rand() % 2 ? @"Nice nice!" : @"Well done!";  } completion:nil];

Swift 3, 4, 5

UIView.transition(with: label,              duration: 0.25,               options: .transitionCrossDissolve,            animations: { [weak self] in                self?.label.text = (arc4random()() % 2 == 0) ? "One" : "Two"         }, completion: nil)

Objective-C

To achieve a true cross-dissolve transition (old label fading out while new label fading in), you don't want fade to invisible. It would result in unwanted flicker even if text is unchanged.

Use this approach instead:

CATransition *animation = [CATransition animation];animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];animation.type = kCATransitionFade;animation.duration = 0.75;[aLabel.layer addAnimation:animation forKey:@"kCATransitionFade"];// This will fade:aLabel.text = "New"

Also see:Animate UILabel text between two numbers?

Demonstration in iOS 10, 9, 8:

Tested with Xcode 8.2.1 & 7.1, ObjectiveC on iOS 10 to 8.0.

► To download the full project, search for SO-3073520 in Swift Recipes.

Swift 4

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

Invocation looks like this:

// This will fadeaLabel.fadeTransition(0.4)aLabel.text = "text"

► Find this solution on GitHub and additional details on Swift Recipes.