理解 UIViewRepresentable

斯威夫特 5.0 iOS 13

尝试了解 UIViewRepresentable 的工作原理，并将这个简单的示例放在一起，几乎就这样了，但也许完全是无稽之谈。是的，我知道 SwiftUI 中已经有一个 tapGesture，这只是一个测试。

无法编译，因为它说在从初始化程序返回之前不会在所有路径上调用“super.init”，我尝试并设置了它，但显然不正确。

import SwiftUI

struct newView: UIViewRepresentable {

typealias UIViewType = UIView
var v = UIView()

func updateUIView(_ uiView: UIView, context: Context) {
  v.backgroundColor = UIColor.yellow
}


func makeUIView(context: Context) -> UIView {
  let tapGesture = UITapGestureRecognizer(target: self, action: #selector(Coordinator.handleTap(sender:)))
  v.addGestureRecognizer(tapGesture)
  return v
}

func makeCoordinator() -> newView.Coordinator {
  Coordinator(v)
}

final class Coordinator: UIView {
  private let view: UIView

init(_ view: UIView) {
    self.view = view
}

required init?(coder: NSCoder) {
  fatalError("init(coder:) has not been implemented")
}

@objc func handleTap(sender: UITapGestureRecognizer) {
    print("tap")
  }
 }

}

只需让你的Coordinator is a NSObject，它通常扮演桥梁/控制器/委托/演员角色，但不扮演演示角色，所以不应该is-a-UIView

final class Coordinator: NSObject {
  private let view: UIView

init(_ view: UIView) {
    self.view = view
}

还有一个...

func makeUIView(context: Context) -> UIView {
  // make target a coordinator, which is already present in context !!
  let tapGesture = UITapGestureRecognizer(target: context.coordinator, 
        action: #selector(Coordinator.handleTap(sender:)))
  v.addGestureRecognizer(tapGesture)
  return v
}