SwiftUI - 如何从 SwiftUI 访问 UIHostingController答案

【问题标题】：SwiftUI - How to access UIHostingController from SwiftUISwiftUI - 如何从 SwiftUI 访问 UIHostingController
【发布时间】：2021-07-23 10:44:35
【问题描述】：

我有 SwiftUI 页面，它是从 UIKit 视图导航的。我想给这个页面设置一个标题，我正在做的是

// code of UIKit view
let controller = UIHostingController(rootView: SwiftUIView())
controller.title = "title"
MyNavigationManager.present(controller)

有没有办法可以在 SwiftUI 中访问主机控制器？

然后我可以编写如下代码 self.hostingController?.title = "title"

【问题讨论】：

最后我选择了一个简单的方法，在宿主控制器中，将 self 传递给 SwiftUI rootView.hostingController = self

标签： swiftui uihostingcontroller

【解决方案1】：

这是一个可能方法的演示 - 使用外部配置包装类来保存到控制器的弱链接并将其注入到 SwiftUI 视图中（作为替代，也可以使其 ObservableObject 与其他全局属性和逻辑相结合)。

使用 Xcode 12.5 / iOS 14.5 测试

class Configuration {
    weak var hostingController: UIViewController?    // << wraps reference
}

struct SwiftUIView: View {
    let config: Configuration   // << reference here

    var body: some View {
        Button("Demo") {
            self.config.hostingController?.title = "New Title"
        }
    }
}

let configuration = ExtConfiguration()
let controller = UIHostingController(rootView: SwiftUIView(config: configuration))

// injects here, because `configuration` is a reference !!
configuration.hostingController = controller

controller.title = "title"
MyNavigationManager.present(controller)

【讨论】：

【解决方案2】：

我选择了一个不同的选项 - 子类 NSHostingController 以便它提供自己作为环境变量。

struct SwiftUIView: View {
    @EnvironmentObject var host:HSHostWrapper

    var body: some View {
        Button("Dismiss") {
            host.controller?.dismiss(self)
        }
    }
}

let controller = HSHostingController(rootView: SwiftUIView())

这是通过以下 HSHostingController 实现的（在 HSSwiftUI package 中可用）

import Foundation
import SwiftUI


#if os(iOS) || os(tvOS)
    import UIKit
    public typealias ViewController = UIViewController
    public typealias HostingController = UIHostingController
#elseif os(OSX)
    import AppKit
    public typealias ViewController = NSViewController
    public typealias HostingController = NSHostingController
#endif

public class HSHostWrapper:ObservableObject {
    public weak var controller:ViewController?
}


/// allows root view (and children) to access the hosting controller by adding
/// @EnvironmentObject var host:HSHostWrapper
/// then e.g. host.controller?.dismiss()
public class HSHostingController<Content>:HostingController<ModifiedContent<Content,SwiftUI._EnvironmentKeyWritingModifier<HSHostWrapper?>>> where Content : View {
    
    public init(rootView:Content) {
        let container = HSHostWrapper()
        let modified = rootView.environmentObject(container) as! ModifiedContent<Content, _EnvironmentKeyWritingModifier<HSHostWrapper?>>
        super.init(rootView: modified)
        container.controller = self
    }
  
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

【讨论】：