SwiftUI 使用 UIKit 控件

由于 SwiftUI 才出来不久，所以有些功能不太好实现，好在苹果提供了接口帮助我们把 UIKit 控件转换为 SwiftUI 使用的控件。

1. UIView 使用 UIViewRepresentable 协议

struct AppleIDLoginButton: UIViewRepresentable {
    private let type: ASAuthorizationAppleIDButton.ButtonType
    private let style: ASAuthorizationAppleIDButton.Style

    init(type: ASAuthorizationAppleIDButton.ButtonType = .default,
         style: ASAuthorizationAppleIDButton.Style = .white) {
        self.type = type
        self.style = style
    }

    func makeUIView(context: UIViewRepresentableContext<AppleIDLoginButton>) -> ASAuthorizationAppleIDButton {
        return .init(type: type, style: style)
    }

    func updateUIView(_ uiView: ASAuthorizationAppleIDButton, context: UIViewRepresentableContext<AppleIDLoginButton>) {

    }
}

初始化时会调用 makeUIView 方法，状态更新时会调用updateUIView 方法，具体调用时机可自己测试。

使用：

AppleIDLoginButton(type: .default)
    .frame(height: 44)
    .onTapGesture {
        // code...
}

2. UIViewController 使用 UIViewControllerRepresentable 协议

UIViewControllerRepresentable 协议提供方法与UIViewRepresentable 类似。这里使用 SwiftUI 与 Combine 编程 中的代码。

struct SafariView: UIViewControllerRepresentable {
    let url: URL
    let onFinished: () -> Void

    func makeUIViewController(context: UIViewControllerRepresentableContext<SafariView>) -> SFSafariViewController {
        let controller = SFSafariViewController(url: url)
        controller.delegate = context.coordinator
        return controller
    }

    func updateUIViewController(
        _ uiViewController: SFSafariViewController,
        context: UIViewControllerRepresentableContext<SafariView>) {

    }

    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }

    class Coordinator: NSObject, SFSafariViewControllerDelegate {
        let parent: SafariView

        init(_ parent: SafariView) {
            self.parent = parent
        }

        func safariViewControllerDidFinish(_ controller: SFSafariViewController) {
            parent.onFinished()
        }
    }
}

makeCoordinator 方法在 UIViewRepresentable 协议中也有。