How to create a flashing pointer effect to UIImages in Swift - ios

Question

I'm trying to create a pointer effect in Swift. I have six UIImageView each has a UIImage that are ordered in a circular way. I want to create an animation of having each image flash (as if it's a pointer indication) for a certain duration.
I thought of creating an array with a transparent version of the images and then create an animated sequence from them but the duration gets mixed up.
This is the idea I'm trying to achieve. I want the images to kind of have this flashing effect, one by one.

Answer 1

This is how I accomplished placing views in a circle and making them "flash"..
First I created regular views (I didn't want to use ImageView's but you are okay to change the code however you like)..
I calculated the angle at which the views need to be placed around a centre point with some radius.. to get them to place in a circle.
Next I create an animation function which has both a forward and reverse animation (I couldn't get autoreverses flag to work)..
To get one to display after the other, I simply add a delay (x2 because forward + reverse)..
To figure out when ALL animations have completed, I wrapped the entire function in a CATransaction.
Note: If you don't need the circular placement code, simply remove it. AFAIK, you only need the animation code.
//
// ViewController.swift
// TestSO
//
// Created by Brandon on 2018-03-03.
// Copyright © 2018 XIO. All rights reserved.
//
import UIKit
extension UIColor {
class func random() -> UIColor {
let rand = { (max: CGFloat) -> CGFloat in
let rnd = CGFloat(arc4random()) / CGFloat(UInt32.max)
return rnd * max
}
return UIColor(red: rand(1.0), green: rand(1.0), blue: rand(1.0), alpha: 1.0)
}
}
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let makeView = { () -> UIView in
let view = UIView()
view.backgroundColor = UIColor.random()
view.frame = CGRect(x: 0.0, y: 0.0, width: 50.0, height: 50.0)
self.view.addSubview(view)
return view
}
let imageViews = [
makeView(),
makeView(),
makeView(),
makeView(),
makeView(),
makeView()
]
let locationForView = { (angle: CGFloat, center: CGPoint, radius: CGFloat) -> CGPoint in
let angle = angle * CGFloat.pi / 180.0
return CGPoint(x: center.x - radius * cos(angle), y: center.y + radius * sin(angle))
}
for i in 0..<imageViews.count {
let center = self.view.center
let radius = ((150.0 + imageViews[i].bounds.size.width) / 2.0)
let count = imageViews.count
imageViews[i].center = locationForView(((360.0 / CGFloat(count)) * CGFloat(i)) + 90.0, center, radius)
}
self.animate(views: imageViews.reversed(), duration: 3.0, intervalDelay: 0.5)
}
private func animate(views: [UIView], duration: TimeInterval, intervalDelay: TimeInterval) {
CATransaction.begin()
CATransaction.setCompletionBlock {
print("COMPLETED ALL ANIMATIONS")
}
var delay: TimeInterval = 0.0
let interval = duration / TimeInterval(views.count)
for view in views {
let colour = view.backgroundColor
let transform = view.transform
UIView.animate(withDuration: interval, delay: delay, options: [.curveEaseIn], animations: {
view.backgroundColor = UIColor.red
view.transform = CGAffineTransform(scaleX: 1.2, y: 1.2)
}, completion: { (finished) in
UIView.animate(withDuration: interval, delay: 0.0, options: [.curveEaseIn], animations: {
view.backgroundColor = colour
view.transform = transform
}, completion: { (finished) in
})
})
delay += (interval * 2.0) + intervalDelay
}
CATransaction.commit()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}