Swift to SwiftUI migration issue - ios

Question

So I am not fully understanding how this needs to be implemented in SwiftUI for it to work properly.
I have the following code:
class RulerView: UIView {
// MARK: - Constants
private struct Constants {
static let labelWidth: CGFloat = 100
static let labelHeight: CGFloat = 20
static let labelMarginTop: CGFloat = 5
static let rulerHeight: CGFloat = 100
}
// MARK: - Properties
override var tintColor: UIColor! {
didSet { _updateStyle().setNeedsDisplay() }
}
internal let unit: Length.Unit
internal let length: CGFloat
private var lineWidth: CGFloat
private var replicatorLayer: CAReplicatorLayer?
private var labels: [UILabel]?
private var lengthUnitWidth: CGFloat {
switch unit {
case .centimeter:
return Length.pixels(fromCentimeter: 1.0)
case .inch:
return Length.pixels(fromInch: 1.0)
}
}
// MARK: - View Life Cycle
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
/*
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
*/
init(unit: Length.Unit, length: CGFloat, lineWidth: CGFloat) {
self.unit = unit
self.length = length
self.lineWidth = lineWidth
super.init(frame: .zero)
let rulerWidth = lengthUnitWidth * length
frame = .init(x: 0, y: 0, width: rulerWidth, height: Constants.rulerHeight)
_setupLabels()
}
override func didMoveToWindow() {
super.didMoveToWindow()
_updateStyle()
}
override func draw(_ rect: CGRect) {
super.draw(rect)
replicatorLayer?.removeFromSuperlayer()
replicatorLayer = CAReplicatorLayer()
if let replicatorLayer = replicatorLayer {
replicatorLayer.instanceCount = Int(ceil(length))
replicatorLayer.instanceTransform = CATransform3DMakeTranslation(lengthUnitWidth, 0, 0)
let unitLayer = LengthUnitLayer(unit: unit, lineWidth: lineWidth, lineColor: tintColor.cgColor, height: frame.height)
unitLayer.frame = CGRect(x: -lineWidth / 2, y: 0, width: unitLayer.bounds.width, height: (bounds.height - Constants.labelHeight - Constants.labelMarginTop))
unitLayer.setNeedsDisplay()
replicatorLayer.addSublayer(unitLayer)
layer.addSublayer(replicatorLayer)
}
labels?.enumerated().forEach { (offset, element) in
element.frame = .init(x: (CGFloat(offset) * lengthUnitWidth - Constants.labelWidth / 2),
y: (bounds.height - Constants.labelHeight),
width: Constants.labelWidth,
height: Constants.labelHeight)
}
}
// MARK: - Setup
#discardableResult
private func _setupLabels() -> Self {
labels?.forEach { $0.removeFromSuperview() }
labels = [UILabel]()
for i in 0...Int(ceil(length)) {
let label = UILabel()
label.text = "\(i)"
label.textAlignment = .center
addSubview(label)
labels?.append(label)
}
return self
}
// MARK: - Layout
#discardableResult
private func _updateStyle() -> Self {
labels?.forEach { $0.textColor = tintColor }
return self
}
}
And I am trying to call it in the ContentView as such:
var viewSize = UIScreen.main.bounds.size
var body: some View {
RulerView(coder: viewSize)
}
But it is not working? Does anyone know how I can resolve this?

Answer 1

The UIView needs to be wrapped into UIViewRepresentable to be used in SwiftUI, like below.
public struct RulerViewRep: UIViewRepresentable {
public func makeUIView(context: Context) -> RulerView {
return RulerView()
}
public func updateUIView(_ uiView: RulerView, context: Context) {
}
}
and then use it
var body: some View {
// by default consumes all space, so UIScreen.main.bounds not needed
RulerView()
}