将值从 swift viewcontroller 传递给 swiftui，然后再返回答案

【问题标题】：passing a value from swift viewcontroller to swiftui and then back again将值从 swift viewcontroller 传递给 swiftui，然后再返回
【发布时间】：2021-04-07 22:33:27
【问题描述】：

所以使用 UIHostingController 从旧的视图控制器打开一个 swiftUI 视图。打算在花哨的 swiftui 界面中进行一些编辑，然后当我关闭 swiftui 视图时想要将编辑后的值传递回原始视图控制器。

我可以将值转移到 swiftui 视图中，但考虑如何取回它？寻找快速的方向。是协议还是可观察的。正确的方法是什么

将价值从 VC 传递到 SwiftUI，这样说：但要收回价值 ??

var selectedValue:String = "this is the selected text to edit"

let swiftUIView = swiftUIEditView(valueSelected: selectedValue)

let hostingController = UIHostingController(rootView: swiftUIView)
present(hostingController, animated: true, completion: nil)

【问题讨论】：

标签： swift core-data swiftui

【解决方案1】：

有很多方法可以做到这一点，但我更喜欢闭包。您可以使用dismissedWithString 闭包将值传回，如下所示：

struct SwiftUIEditView: View {
    
    @State var valueSelected: String
    var dismissedWithString: ((String) -> Void)? /// closure here!
    
    var body: some View {
        VStack {
            TextField("Text field", text: $valueSelected)
                .multilineTextAlignment(.center)
            
            Button(action: {
                dismissedWithString?(valueSelected) /// call the closure and pass in the text
            }) {
                Text("Return string and dismiss")
            }
        }
    }
}

那么你的视图控制器将是这样的：

class ViewController: UIViewController {
    var selectedValue: String = "this is the selected text to edit"

    func presentEditView() {
        
        var viewController: UIViewController?
        
        let contentView = SwiftUIEditView(valueSelected: selectedValue) { [weak self] returnedString in
            
            /// dismiss UIHostingController - it's a trailing closure, so you don't need to put the `dismissSelf`
            viewController?.dismiss(animated: true, completion: nil)
            
            self?.selectedValue = returnedString /// assign
            print(returnedString) /// will be the value
        }
        
        viewController = UIHostingController(rootView: contentView)
        
        if let vc = viewController { /// viewController will never be nil, but I don't like to force-unwrap
            self.present(vc, animated: true, completion: nil)
        }
    }
}

【讨论】：