SwiftUI按钮点击展示Objective-C UIViewController的实现方案

问题背景 #

刚接触SwiftUI，在现有Objective-C项目中引入SwiftUI模块，通过UIHostingController在SwiftViewControllerUsedToPresentSwiftUI中初始化SwiftUI视图（struct ContentView: View），代码如下，这部分运行正常：

let hostingController = UIHostingController.init(rootView: ContentView())

需求是在SwiftUI视图的按钮点击时，调用项目中带关联xib的现有MyExistingUIViewController，理想实现代码如下：

let myExistingUIViewController = MyExistingUIViewController(nibName: "MyExistingUIViewController", bundle: nil)
myExistingUIViewController.modalPresentationStyle = .formSheet
present(myExistingUIViewController, animated: true, completion: nil)

尝试直接通过宿主VC调用时，出现以下错误：

[Presentation] Attempt to present <MyExistingUIViewController: 0x7f7a67827c00> on <SwiftViewControllerUsedToPresentSwiftUI: 0x7f7a64720da0> (from <SwiftViewControllerUsedToPresentSwiftUI: 0x7f7a64720da0>) whose view is not in the window hierarchy.

后续按照建议用UIViewControllerRepresentable包装现有VC：

import Foundation
import SwiftUI

struct MyExistingUIViewControllerWrapper: UIViewControllerRepresentable{
    func makeUIViewController(context: Context) -> MyExistingUIViewController {
        let vc = MyExistingUIViewController(nibName: "MyExistingView", bundle: nil)
        return vc
    }

    func updateUIViewController(_ uiViewController: MyExistingUIViewController, context: Context) {
        // 相关代码
    }
}

通过SwiftUI的.sheet调用时：

.sheet(isPresented: $showingWrapperView){
    MyExistingUIViewControllerWrapper()
}

但无法以formSheet样式展示，而现有xib对应的VC本身是formSheet样式。

解决方案 #

页面流转路径为：Objective-C View Controller → SwiftUI → Objective-C Form Sheet，通过从初始的FirstObjCViewController向SwiftUI视图传递两个闭包Handler，实现需求：

• 一个Handler用于关闭当前SwiftUI视图
• 另一个Handler用于关闭SwiftUI视图，并从FirstObjCViewController打开目标FormSheet类型的MyExistingUIViewController

代码实现 #

1. Objective-C侧创建SwiftUI视图的代码：

UIViewController *newSwiftUIView = [NewSwiftUIView makeNewSwiftUIView WithSomeFirstArg:someFirstArg 
                                                                           closeHandler:^{
                                                                               [[self presentedViewController] dismissViewControllerAnimated:YES completion:nil];
                                                                           } 
                                 closeAndOpenMyExistingUIViewControllerHandler:^{
                                                                               [[self presentedViewController] dismissViewControllerAnimated:YES completion:nil];
                                                                               [self OpenMyExistingUIViewController]; // 此方法在FirstObjCViewController中定义，负责以FormSheet样式打开目标VC
                                                                           }];

2. Swift侧接收Handler的方法定义：

@objc static func makeNewSwiftUIView(someFirstArg: NSArray, 
                                     closeHandler: @escaping (() -> Void), 
                                     closeAndOpenMyExistingUIViewControllerHandler: @escaping (() -> Void)) -> UIViewController

这种实现方式运行流畅、代码简洁，可直接复用现有Objective-C侧的VC展示逻辑，保证FormSheet样式正常生效。

内容的提问来源于stack exchange，提问作者user1664018