CODEWITHSUNDEEP
iosswiftanimationuiviewanimation
cmii
cmii

Reputation: 3636

Random/Irregular pulse animation on imageview in SWIFT

I need to implement a random "pulse" animation on an imageview. Random, because I don't want a simple loop animation which repeat it forever each x seconds. The pulsation has to be irregular.

I need a random delay, random duration, and if it's possible random value for fromValue and toValue.

My code for a simple pulse animation, repeat each 5 sec, with an opacity to 0 from 1 :

    var pulseAnimation:CABasicAnimation = CABasicAnimation(keyPath: "opacity")
    pulseAnimation.duration = 5.0
    pulseAnimation.fromValue = NSNumber(float: 0.0)
    pulseAnimation.toValue = NSNumber(float: 1.0)
    pulseAnimation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
    pulseAnimation.autoreverses = true
    pulseAnimation.repeatCount = Float.infinity
    myimageview.layer.addAnimation(pulseAnimation, forKey: "opacity")

If I write something like :

    pulseAnimation.duration = arc4random(....) //I will have a "fixed" random value

How can I do to implement irregular values ?

Upvotes: 0

Views: 1815

Answers (2)

cmii
cmii

Reputation: 3636

Ok I found a method :

    for loopNumber in 1...5 {

        let myImageView = UIImageView()
        myImageView.image = UIImage(named: "nameImageView")
        myImageView.frame = CGRect(x: 0, y: 0, width: 100, height: 200)
        self.view.addSubview(myImageView)

        var pulseAnimation = CABasicAnimation(keyPath: "opacity")

        pulseAnimation.fromValue = Double(arc4random_uniform(6)+1)/10
        pulseAnimation.toValue = Double(arc4random_uniform(6)+2)/10
        pulseAnimation.duration = Double(loopNumber)            
        pulseAnimation.repeatCount = Float.infinity

        myImageView.layer.addAnimation(pulseAnimation, forKey: "opacity")
    }

Upvotes: 1

zaph
zaph

Reputation: 112855

arc4random() and arc4random_uniform() are as random as you can get. No seeding is required and they are cryptographic quality.

For a range use arc4random_uniform() instead of using the modular operator on arc4random().

What you don't want to use is rand().

Upvotes: 2

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