CAShapeLayer with different Colors - ios

Question

I have a CAShapeLayer based on this answer that animates along with a UISlider.
It works fine but as the shapeLayer follows along its just 1 red CAGradientLayer color. What I want is the shapeLayer to change colors based on certain points of the slider. An example is at 0.4 - 0.5 it's red, 0.7-0.8 red, 0.9-0.95 red. Those aren't actual values, the actual values will vary. I figure that any time it doesn't meet the condition to turn red it should probably just be a clear color, which will just show the black track underneath it. The result would look something like this (never mind the shape)
The red colors are based on the user scrubbing the slider and the letting go. The different positions of the slider that determine the red color is based on whatever condition. How can I do this.
UISlider
lazy var slider: UISlider = {
let s = UISlider()
s.translatesAutoresizingMaskIntoConstraints = false
s.minimumTrackTintColor = .blue
s.maximumTrackTintColor = .white
s.minimumValue = 0
s.maximumValue = 1
s.addTarget(self, action: #selector(onSliderChange), for: .valueChanged)
return s
s.addTarget(self, action: #selector(onSliderEnded), for: [.touchUpInside, .touchUpOutside, .touchCancel])
return s
}()
lazy var progressView: GradientProgressView = {
let v = GradientProgressView()
v.translatesAutoresizingMaskIntoConstraints = false
return v
}()
#objc fileprivate func onSliderChange(_ slider: UISlider) {
let condition: Bool = // ...
let value = slider.value
progressView.setProgress(CGFloat(value), someCondition: condition, slider_X_Position: slider_X_PositionInView())
}
#objc fileprivate func onSliderEnded(_ slider: UISlider) {
let value = slider.value
progressView.resetProgress(CGFloat(value))
}
// ... progressView is the same width as the the slider
func slider_X_PositionInView() -> CGFloat {
let trackRect = slider.trackRect(forBounds: slider.bounds)
let thumbRect = slider.thumbRect(forBounds: slider.bounds,
trackRect: trackRect,
value: slider.value)
let convertedThumbRect = slider.convert(thumbRect, to: self.view)
return convertedThumbRect.midX
}
GradientProgressView:
public class GradientProgressView: UIView {
var shapeLayer: CAShapeLayer = {
// ...
}()
private var trackLayer: CAShapeLayer = {
let trackLayer = CAShapeLayer()
trackLayer.strokeColor = UIColor.black.cgColor
trackLayer.fillColor = UIColor.clear.cgColor
trackLayer.lineCap = .round
return trackLayer
}()
private var gradient: CAGradientLayer = {
let gradient = CAGradientLayer()
let redColor = UIColor.red.cgColor
gradient.colors = [redColor, redColor]
gradient.locations = [0.0, 1.0]
gradient.startPoint = CGPoint(x: 0, y: 0)
gradient.endPoint = CGPoint(x: 1, y: 0)
return gradient
}()
// ... add the above layers as subLayers to self ...
func updatePaths() { // added in layoutSubviews
let lineWidth = bounds.height / 2
trackLayer.lineWidth = lineWidth * 0.75
shapeLayer.lineWidth = lineWidth
let path = UIBezierPath()
path.move(to: CGPoint(x: bounds.minX + lineWidth / 2, y: bounds.midY))
path.addLine(to: CGPoint(x: bounds.maxX - lineWidth / 2, y: bounds.midY))
trackLayer.path = path.cgPath
shapeLayer.path = path.cgPath
gradient.frame = bounds
gradient.mask = shapeLayer
shapeLayer.duration = 1
shapeLayer.strokeStart = 0
shapeLayer.strokeEnd = 0
}
public func setProgress(_ progress: CGFloat, someCondition: Bool, slider_X_Position: CGFloat) {
// slider_X_Position might help with shapeLayer's x position for the colors ???
if someCondition {
// redColor until the user lets go
} else {
// otherwise always a clearColor
}
shapeLayer.strokeEnd = progress
}
}
public func resetProgress(_ progress: CGFloat) {
// change to clearColor after finger is lifted
}
}

Answer 1

To get this:
We can use a CAShapeLayer for the red "boxes" and a CALayer as a .mask on that shape layer.
To reveal / cover the boxes, we set the frame of the mask layer to a percentage of the width of the bounds.
Here's a complete example:
class StepView: UIView {
public var progress: CGFloat = 0 {
didSet {
setNeedsLayout()
}
}
public var steps: [[CGFloat]] = [[0.0, 1.0]] {
didSet {
setNeedsLayout()
}
}
public var color: UIColor = .red {
didSet {
stepLayer.fillColor = color.cgColor
}
}
private let stepLayer = CAShapeLayer()
private let maskLayer = CALayer()
override init(frame: CGRect) {
super.init(frame: frame)
commonInit()
}
required init?(coder: NSCoder) {
super.init(coder: coder)
commonInit()
}
private func commonInit() {
backgroundColor = .black
layer.addSublayer(stepLayer)
stepLayer.fillColor = color.cgColor
stepLayer.mask = maskLayer
// mask layer can use any solid color
maskLayer.backgroundColor = UIColor.white.cgColor
}
override func layoutSubviews() {
super.layoutSubviews()
stepLayer.frame = bounds
let pth = UIBezierPath()
steps.forEach { pair in
// rectangle for each "percentage pair"
let w = bounds.width * (pair[1] - pair[0])
let b = UIBezierPath(rect: CGRect(x: bounds.width * pair[0], y: 0, width: w, height: bounds.height))
pth.append(b)
}
stepLayer.path = pth.cgPath
// update frame of mask layer
var r = bounds
r.size.width = bounds.width * progress
maskLayer.frame = r
}
}
class StepVC: UIViewController {
let stepView = StepView()
override func viewDidLoad() {
super.viewDidLoad()
stepView.translatesAutoresizingMaskIntoConstraints = false
let slider = UISlider()
slider.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(stepView)
view.addSubview(slider)
let g = view.safeAreaLayoutGuide
NSLayoutConstraint.activate([
stepView.topAnchor.constraint(equalTo: g.topAnchor, constant: 80.0),
stepView.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
stepView.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
stepView.heightAnchor.constraint(equalToConstant: 40.0),
slider.topAnchor.constraint(equalTo: stepView.bottomAnchor, constant: 40.0),
slider.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
slider.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
])
let steps: [[CGFloat]] = [
[0.1, 0.3],
[0.4, 0.5],
[0.7, 0.8],
[0.9, 0.95],
]
stepView.steps = steps
slider.addTarget(self, action: #selector(sliderChanged(_:)), for: .valueChanged)
}
#objc func sliderChanged(_ sender: UISlider) {
// disable CALayer "built-in" animations
CATransaction.setDisableActions(true)
stepView.progress = CGFloat(sender.value)
CATransaction.commit()
}
}
Edit
I'm still not clear on your 0.4 - 0.8 requirement, but maybe this will help get you on your way:
Please note: this is Example Code Only!!!
struct RecordingStep {
var color: UIColor = .black
var start: Float = 0
var end: Float = 0
var layer: CALayer!
}
class StepView2: UIView {
public var progress: Float = 0 {
didSet {
// move the progress layer
progressLayer.position.x = bounds.width * CGFloat(progress)
// if we're recording
if isRecording {
let i = theSteps.count - 1
guard i > -1 else { return }
// update current "step" end
theSteps[i].end = progress
setNeedsLayout()
}
}
}
private var isRecording: Bool = false
private var theSteps: [RecordingStep] = []
private let progressLayer = CAShapeLayer()
public func startRecording(_ color: UIColor) {
// create a new "Recording Step"
var st = RecordingStep()
st.color = color
st.start = progress
st.end = progress
let l = CALayer()
l.backgroundColor = st.color.cgColor
layer.insertSublayer(l, below: progressLayer)
st.layer = l
theSteps.append(st)
isRecording = true
}
public func stopRecording() {
isRecording = false
}
override init(frame: CGRect) {
super.init(frame: frame)
commonInit()
}
required init?(coder: NSCoder) {
super.init(coder: coder)
commonInit()
}
private func commonInit() {
backgroundColor = .black
progressLayer.lineWidth = 3
progressLayer.strokeColor = UIColor.green.cgColor
progressLayer.fillColor = UIColor.clear.cgColor
layer.addSublayer(progressLayer)
}
override func layoutSubviews() {
super.layoutSubviews()
// only set the progessLayer frame if the bounds height has changed
if progressLayer.frame.height != bounds.height + 7.0 {
let r: CGRect = CGRect(origin: .zero, size: CGSize(width: 7.0, height: bounds.height + 7.0))
let pth = UIBezierPath(roundedRect: r, cornerRadius: 3.5)
progressLayer.frame = r
progressLayer.position = CGPoint(x: 0, y: bounds.midY)
progressLayer.path = pth.cgPath
}
theSteps.forEach { st in
let x = bounds.width * CGFloat(st.start)
let w = bounds.width * CGFloat(st.end - st.start)
let r = CGRect(x: x, y: 0.0, width: w, height: bounds.height)
st.layer.frame = r
}
}
}
class Step2VC: UIViewController {
let stepView = StepView2()
let actionButton: UIButton = {
let b = UIButton()
b.backgroundColor = .lightGray
b.setImage(UIImage(systemName: "play.fill"), for: [])
b.tintColor = .systemGreen
return b
}()
var timer: Timer!
let colors: [UIColor] = [
.red, .systemBlue, .yellow, .cyan, .magenta, .orange,
]
var colorIdx: Int = -1
var action: Int = 0
override func viewDidLoad() {
super.viewDidLoad()
stepView.translatesAutoresizingMaskIntoConstraints = false
actionButton.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(stepView)
view.addSubview(actionButton)
let g = view.safeAreaLayoutGuide
NSLayoutConstraint.activate([
stepView.topAnchor.constraint(equalTo: g.topAnchor, constant: 80.0),
stepView.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
stepView.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
stepView.heightAnchor.constraint(equalToConstant: 40.0),
actionButton.topAnchor.constraint(equalTo: stepView.bottomAnchor, constant: 40.0),
actionButton.widthAnchor.constraint(equalToConstant: 80.0),
actionButton.centerXAnchor.constraint(equalTo: g.centerXAnchor),
])
actionButton.addTarget(self, action: #selector(btnTap(_:)), for: .touchUpInside)
}
#objc func timerFunc(_ timer: Timer) {
// don't set progress > 1.0
stepView.progress = min(stepView.progress + 0.005, 1.0)
if stepView.progress >= 1.0 {
timer.invalidate()
actionButton.isHidden = true
}
}
#objc func btnTap(_ sender: UIButton) {
switch action {
case 0:
// this will run for 15 seconds
timer = Timer.scheduledTimer(timeInterval: 0.075, target: self, selector: #selector(timerFunc(_:)), userInfo: nil, repeats: true)
stepView.stopRecording()
actionButton.setImage(UIImage(systemName: "record.circle"), for: [])
actionButton.tintColor = .red
action = 1
case 1:
colorIdx += 1
stepView.startRecording(colors[colorIdx % colors.count])
actionButton.setImage(UIImage(systemName: "stop.circle"), for: [])
actionButton.tintColor = .black
action = 2
case 2:
stepView.stopRecording()
actionButton.setImage(UIImage(systemName: "record.circle"), for: [])
actionButton.tintColor = .red
action = 1
default:
()
}
}
}
For future reference, when posting here, it's probably a good idea to fully explain what you're trying to do. Showing code you're working on is important, but if it's really only sorta related to your actual goal, it makes this process pretty difficult.