How can I centre a circular progress bar in a UIView using Swift? - swift

Question

I'm having quite a bit of difficulty simply ensuring a circular progress bar is always in the centre of the UIView it is associated to.
This is what is happening:
Ignore the grey region, this is simply the UIView on a placeholder card. The red is the UIView I have added as an outlet to the UIViewController.
Below is the code for the class that I have made:
class CircleProgress: UIView {
override init(frame: CGRect) {
super.init(frame: frame)
setupView()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
setupView()
}
var progressLyr = CAShapeLayer()
var trackLyr = CAShapeLayer()
var progressClr = UIColor.red {
didSet {
progressLyr.strokeColor = progressClr.cgColor
}
}
var trackClr = UIColor.black {
didSet {
trackLyr.strokeColor = trackClr.cgColor
}
}
private func setupView() {
self.backgroundColor = UIColor.red
let centre = CGPoint(x: frame.size.width/2, y: frame.size.height/2)
let circlePath = UIBezierPath(arcCenter: centre,
radius: 10,
startAngle: 0,
endAngle: 2 * CGFloat.pi,
clockwise: true)
trackLyr.path = circlePath.cgPath
trackLyr.fillColor = UIColor.clear.cgColor
trackLyr.strokeColor = trackClr.cgColor
trackLyr.lineWidth = 5.0
trackLyr.strokeEnd = 1.0
layer.addSublayer(trackLyr)
}
}
The aim is simply to have all 4 edges of the black circle touching the edges of the red square.
Any help is hugely appreciated. I'm thinking it must be too obvious but this has cost me too many hours tonight. :)

Answer 1

The problem is that there is no frame being passed when creating the object. No need for changing anything to your code. For sure you have to change the width and the height to whatever you want.
Here is an example...
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
self.view.backgroundColor = .white
// Add circleProgress
addCircleProgress()
}
private func addCircleProgress() {
let circleProgress = CircleProgress(frame: CGRect(x: self.view.center.x - 50, y: self.view.center.x - 50, width: 100, height: 100))
self.view.addSubview(circleProgress)
}
}
class CircleProgress: UIView {
override init(frame: CGRect) {
super.init(frame: frame)
setupView()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
var progressLyr = CAShapeLayer()
var trackLyr = CAShapeLayer()
var progressClr = UIColor.red {
didSet {
progressLyr.strokeColor = progressClr.cgColor
}
}
var trackClr = UIColor.black {
didSet {
trackLyr.strokeColor = trackClr.cgColor
}
}
private func setupView() {
self.backgroundColor = UIColor.red
let centre = CGPoint(x: frame.size.width/2, y: frame.size.height/2)
let circlePath = UIBezierPath(arcCenter: centre,
radius: 50,
startAngle: 0,
endAngle: 2 * CGFloat.pi,
clockwise: true)
trackLyr.path = circlePath.cgPath
trackLyr.fillColor = UIColor.clear.cgColor
trackLyr.strokeColor = trackClr.cgColor
trackLyr.lineWidth = 5.0
trackLyr.strokeEnd = 1.0
layer.addSublayer(trackLyr)
}
}

Answer 2

A few suggestions:
I’d suggest making this CircularProgress take up the whole view. If you want this to be inset within the view, then, fine, add a property for that. In my example below, I created a property called inset to capture this value.
Make sure to update your path in layoutSubviews. Especially if you use constraints, you want this to respond to size changes. So add these layers from init, but update the path in layoutSubviews.
Don’t reference frame (which is the location within the superview coordinate system). Use bounds. And inset it by half the line width, so the circle doesn’t exceed the bounds of the view.
You created a progress color and progress layer, but didn’t use either one. I’ve guessed you wanted that to show the progress within the track.
You are stroking your path from 0 to 2π. People tend to expect these circular progress views to start from -π/2 (12 o’clock) and progress to 3π/2. So I’ve updated the path to use those values. But use whatever you want.
If you want, you can make it #IBDesignable if you want to see this rendered in IB.
Thus, pulling that together, you get:
#IBDesignable
public class CircleProgress: UIView {
#IBInspectable
public var lineWidth: CGFloat = 5 { didSet { updatePath() } }
#IBInspectable
public var strokeEnd: CGFloat = 1 { didSet { progressLayer.strokeEnd = strokeEnd } }
#IBInspectable
public var trackColor: UIColor = .black { didSet { trackLayer.strokeColor = trackColor.cgColor } }
#IBInspectable
public var progressColor: UIColor = .red { didSet { progressLayer.strokeColor = progressColor.cgColor } }
#IBInspectable
public var inset: CGFloat = 0 { didSet { updatePath() } }
private lazy var trackLayer: CAShapeLayer = {
let layer = CAShapeLayer()
layer.fillColor = UIColor.clear.cgColor
layer.strokeColor = trackColor.cgColor
layer.lineWidth = lineWidth
return layer
}()
private lazy var progressLayer: CAShapeLayer = {
let layer = CAShapeLayer()
layer.fillColor = UIColor.clear.cgColor
layer.strokeColor = progressColor.cgColor
layer.lineWidth = lineWidth
return layer
}()
override init(frame: CGRect = .zero) {
super.init(frame: frame)
setupView()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
setupView()
}
public override func layoutSubviews() {
super.layoutSubviews()
updatePath()
}
}
private extension CircleProgress {
func setupView() {
layer.addSublayer(trackLayer)
layer.addSublayer(progressLayer)
}
func updatePath() {
let rect = bounds.insetBy(dx: lineWidth / 2 + inset, dy: lineWidth / 2 + inset)
let centre = CGPoint(x: rect.midX, y: rect.midY)
let radius = min(rect.width, rect.height) / 2
let path = UIBezierPath(arcCenter: centre,
radius: radius,
startAngle: -.pi / 2,
endAngle: 3 * .pi / 2,
clockwise: true)
trackLayer.path = path.cgPath
trackLayer.lineWidth = lineWidth
progressLayer.path = path.cgPath
progressLayer.lineWidth = lineWidth
}
}
That yields:

Answer 3

Update this function
private func setupView() {
self.backgroundColor = UIColor.red
let centre = CGPoint(x: bounds.midX, y: bounds.midY)
let circlePath = UIBezierPath(arcCenter: centre,
radius: bounds.maxX/2,
startAngle: 0,
endAngle: 2 * CGFloat.pi,
clockwise: true)
trackLyr.path = circlePath.cgPath
trackLyr.fillColor = UIColor.clear.cgColor
trackLyr.strokeColor = trackClr.cgColor
trackLyr.lineWidth = 5.0
trackLyr.strokeEnd = 1.0
layer.addSublayer(trackLyr)
}