了解 UIViewRepresentable

Question

Swift 5.0 iOS 13

试图理解 UIViewRepresentable 是如何工作的，并把这个简单的例子放在一起，几乎已经完成，但也许它完全是胡说八道。是的，我知道SwiftUI中已经有一个tapGesture，这只是一个测试。

不会编译，因为它说 'super.init' 在从初始化程序返回之前没有在所有路径上调用，我尝试设置但显然不正确。

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")
  }
 }

}

Answer 1

那是因为您的 Coordinator 是 UIView 的子类，而您

Must call a designated initializer of the superclass 'UIView'

从 init 返回之前：

init(_ view: UIView) {
    self.view = view
    super.init(frame: .zero) // Or any other frame you need
}

Answer 2

只是让你的Coordinator是一个NSObject，它通常起到bridge/controller/delegate/actor的作用，而不是呈现，所以不应该是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
}

了解 UIViewRepresentable

Understanding UIViewRepresentable

swift

swiftui

uiviewrepresentable