I can't find it documented anywhere, but it appears the backgroundColor property of UILabel is not animatable, as your code works fine with a vanilla UIView. This hack appears to work, however, as long as you don't set the background color of the label view itself:

#import <QuartzCore/QuartzCore.h>...theLabel.layer.backgroundColor = [UIColor whiteColor].CGColor;[UIView animateWithDuration:2.0 animations:^{    theLabel.layer.backgroundColor = [UIColor greenColor].CGColor;} completion:NULL];

Swift

1. (important) Set the UILabel's background color to clear (either in IB or in code). For example:

   override func viewDidLoad() {    super.viewDidLoad()    myLabel.backgroundColor = UIColor.clear}

2. Animate the layer background color.

   @IBAction func animateButtonTapped(sender: UIButton) {    UIView.animate(withDuration: 1.0, animations: {        self.myLabel.layer.backgroundColor = UIColor.red.cgColor    })}

Note that CGColor is added after the UIColor.

Result

Swift 3

To animate your label background color from white to green, set up your label like this:

self.labelCorrection.backgroundColor = UIColor.clearself.labelCorrection.layer.backgroundColor = UIColor.white.cgColor

Animate like this:

UIView.animate(withDuration: 2.0) {     self.labelCorrection.layer.backgroundColor = UIColor.green.cgColor}

To go back to the original state, so you can animate again, make sure you remove animations:

self.labelCorrection.layer.backgroundColor = UIColor.white.cgColorself.labelCorrection.layer.removeAllAnimations()