将@Published属性从视图控制器传递到SwiftUI
将@Published属性从视图控制器传递到SwiftUI
提问于 2020-10-15 00:13:21
假设您有一个遗留的视图控制器，我想在SwiftUI中使用它。视图控制器有一个@Published属性，该属性包含它的当前状态：
class LegacyViewController: UIViewController {
enum State {
case opened
case closed
case halfOpened
}
@Published var state: State
override init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: Bundle?) {
self.state = .closed
super.init(nibName: nil, bundle: nil)
}
override func viewDidLoad() {
super.viewDidLoad()
// state is changed after some time
}
}理想情况下，我希望在SwiftUI中使用它，如下所示：
struct ContentView: View {
@State var state: LegacyViewController.State
var body: some View {
VCWrapper(state: $state).overlay (
Text("\(state)")
)
}
}这意味着我需要实现UIViewControllerRepresentable协议：
struct VCWrapper: UIViewControllerRepresentable {
@Binding var state: LegacyViewController.State
func makeUIViewController(context: Context) -> LegacyViewController {
let vc = LegacyViewController(nibName: nil, bundle: nil)
/// where to perform the actual binding?
return vc
}
func updateUIViewController(_ uiViewController: LegacyViewController, context: Context) {
}
}但是，我在找出从LegacyViewController的state属性到VCWrapper公开的state属性的实际绑定位置时遇到了麻烦。如果LegacyViewController公开了一个委托，我可以通过Coordinator对象实现绑定，但考虑到我没有使用委托对象，我不确定如何做到这一点？
回答 1
Stack Overflow用户
回答已采纳
发布于 2020-10-15 00:51:12
以下是可能的解决方案--使用Combine。使用Xcode12/ iOS 14进行了测试。
import Combine
struct VCWrapper: UIViewControllerRepresentable {
@Binding var state: LegacyViewController.State
func makeUIViewController(context: Context) -> LegacyViewController {
let vc = LegacyViewController(nibName: nil, bundle: nil)
// subscribe to controller state publisher and update bound
// external state
context.coordinator.cancelable = vc.$state
.sink {
DispatchQueue.main.async {
_state.wrappedValue = $0
}
}
return vc
}
func updateUIViewController(_ uiViewController: LegacyViewController, context: Context) {
}
func makeCoordinator() -> Coordinator {
Coordinator()
}
class Coordinator {
var cancelable: AnyCancellable?
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/64357436
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