Circle UIView resize with animation keeping Circle shape - ios

Question

I have a UIView which I am making the background a circular shape with:
self.colourView.layer.cornerRadius = 350
self.colourView.clipsToBounds = true
With the view being a 700 by 700 square.
I am then trying to change the size of this view using:
UIView.animate(withDuration: zoomLength,
delay: 0,
options: .curveEaseIn,
animations: {
self.colorViewWidth.constant = 100
self.colorViewHeight.constant = 100
self.colourView.layer.cornerRadius = 50
self.colourView.clipsToBounds = true
self.view.layoutIfNeeded()
},
completion: { finished in
})
})
The problem with this is the corner radius of the view switch to 50 instantly. So that as the view shrinks in size it doesn't look like a circle shrinking but a square with rounded corners until it reaches the 100 by 100 size.
How can I take a view that circule in shape and shrink it down while maintaining the circlare shape during the animation.

Answer 1

You could always animate the corner radius as well with a CABasicAnimation along side the UIView animations. See example below.
import UIKit
class ViewController: UIViewController {
//cause 'merica
var colorView = UIView()
var button = UIButton()
var colorViewWidth : NSLayoutConstraint!
var colorViewHeight : NSLayoutConstraint!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
colorView.frame = CGRect(x: 0, y: 0, width: 750, height: 750)
colorView.center = self.view.center
colorView.backgroundColor = .blue
colorView.layer.cornerRadius = 350
colorView.clipsToBounds = true
colorView.layer.allowsEdgeAntialiasing = true
colorView.translatesAutoresizingMaskIntoConstraints = false
//set up constraints
colorViewWidth = NSLayoutConstraint(item: colorView, attribute: .width, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1, constant: 750)
colorViewWidth.isActive = true
colorViewHeight = NSLayoutConstraint(item: colorView, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1, constant: 750)
colorViewHeight.isActive = true
self.view.addSubview(colorView)
colorView.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive = true
colorView.centerYAnchor.constraint(equalTo: self.view.centerYAnchor).isActive = true
//button for action
button = UIButton(frame: CGRect(x: 0, y: 0, width: self.view.bounds.width - 20, height: 50))
button.center = self.view.center
button.center.y = self.view.bounds.height - 70
button.addTarget(self, action: #selector(ViewController.pressed(sender:)), for: .touchUpInside)
button.setTitle("Animate", for: .normal)
button.setTitleColor(.blue, for: .normal)
self.view.addSubview(button)
}
func pressed(sender:UIButton) {
self.colorViewWidth.constant = 100
self.colorViewHeight.constant = 100
UIView.animate(withDuration: 1.0,
delay: 0,
options: .curveEaseIn,
animations: {
self.view.layoutIfNeeded()
},
completion: { finished in
})
//animate cornerRadius and update model
let animation = CABasicAnimation(keyPath: "cornerRadius")
animation.duration = 1.0
//super important must match
animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseIn)
animation.fromValue = colorView.layer.cornerRadius
animation.toValue = 50
colorView.layer.add(animation, forKey: nil)
//update model important
colorView.layer.cornerRadius = 50
}
}
Result:

Answer 2

Try to put your image inside a viewDidLayoutSubviews()
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
colourView.layer.cornerRadius = colourView.frame.size.width/2
colourView.layer.masksToBounds = true
colourView.layer.borderWidth = 3.0
colourView.layer.borderColor = UIColor(red: 142.0/255.5, green: 142.0/255.5, blue: 142.0/255.5, alpha: 1.0).cgColor
}
let me know how it goes
Cheers

Answer 3

Regarding animation you need to create the CAShapeLayer object and then set the cgpath of the layer object.
let circleLayer = CAShapeLayer()
let radius = view.bounds.width * 0.5
//Value of startAngle and endAngle should be in the radian.
let path = UIBezierPath(arcCenter: center, radius: radius, startAngle: startAngle, endAngle: endAngle, clockwise: true)
circleLayer.path = path.cgPath
The above will draw the circle for you. After that you can apply the animation on layer object.
let animation = CABasicAnimation(keyPath: "strokeEnd")
animation.fromValue = fromValue//you can update the value here by default it will be 0
animation.toValue = toValue //you can update the value here by default it will be 1
animation.duration = CFTimeInterval(remainingTime)
circleLayer
circleLayer.removeAnimation(forKey: "stroke")
circleLayer.add(animation, forKey: "stroke")