Color cycle not cycling through all colors in swift

Question

Can somebody help me please. I created a color cycle but it's only cycling through yellow and orange (the last 2 colors), instead of all of them. I attached a picture with my code.

Answer 1

The animation block in UIView.animate(...) does not generate a sequence of animations.

So, the code as you're written it does not go from color 0 to 1 to 2 etc.

Instead, you'll want to use Keyframe animation.

Here's a simple example of a view that cycles continuously through the colors array:

class ColorCycleView: UIView {
    
    var colors: [UIColor] = [
        .purple, .blue, .green, .yellow, .orange
    ]
    override func didMoveToSuperview() {
        startAnim()
    }
    func startAnim() {
        // total duration is number of colors (so, 1-second per color change)
        //  if we want 2-seconds per color change, for example, use TimeInterval(colors.count * 2)
        let totalDuration: TimeInterval = TimeInterval(colors.count)
        
        // relative duration is a percentage of the whole
        //  so with 5 colors, for example, it will be 0.2
        let relDuration: CGFloat = 1.0 / CGFloat(colors.count)
        
        // we want each change to start in sequence, so
        //  we'll increment this in our loop below
        //  for example, with 5 colors, the relative start times will be:
        //      0.0, 0.2, 0.4, 0.6, 0.8
        var relStartTime: TimeInterval = 0.0
        
        UIView.animateKeyframes(withDuration: totalDuration, delay: 0.0, options: [.repeat, .autoreverse, .calculationModeCubicPaced], animations: {
            self.colors.forEach { c in
                UIView.addKeyframe(withRelativeStartTime: relStartTime, relativeDuration: relDuration, animations: {
                    self.backgroundColor = c
                })
                relStartTime += relDuration
            }
        })
    }

}

Note that you also don't want to execute this code in layoutSubviews() ... that can be (and very often is) called multiple times.

Either call a "start animating" func from the controller, or trigger it automatically from somewhere like didMoveToSuperview() as shown above.