从 SwiftUI 视图呈现 UIActivityViewController

Question

我正在尝试从 SwiftUI 视图中呈现 UIActivityViewController（共享表）。我创建了一个名为ShareSheet 的视图符合UIViewControllerRepresentable 来配置UIActivityViewController，但实际呈现它并不是那么简单。

struct ShareSheet: UIViewControllerRepresentable {
    typealias UIViewControllerType = UIActivityViewController

    var sharing: [Any]

    func makeUIViewController(context: UIViewControllerRepresentableContext<ShareSheet>) -> UIActivityViewController {
        UIActivityViewController(activityItems: sharing, applicationActivities: nil)
    }

    func updateUIViewController(_ uiViewController: UIActivityViewController, context: UIViewControllerRepresentableContext<ShareSheet>) {

    }
}

通过.sheet 天真地这样做会导致以下结果。

.sheet(isPresented: $showShareSheet) {
    ShareSheet(sharing: [URL(string: "https://example.com")!])
}

有没有办法像通常呈现的那样呈现这个？就像覆盖半个屏幕一样？

Answer 1

希望对你有帮助，

struct ShareSheetView: View {
    var body: some View {
        Button(action: actionSheet) {
            Image(systemName: "square.and.arrow.up")
                .resizable()
                .aspectRatio(contentMode: .fit)
                .frame(width: 36, height: 36)
        }
    }
    
    func actionSheet() {
        guard let data = URL(string: "https://www.apple.com") else { return }
        let av = UIActivityViewController(activityItems: [data], applicationActivities: nil)
        UIApplication.shared.windows.first?.rootViewController?.present(av, animated: true, completion: nil)
    }
}

Answer 2

有一个UIModalPresentationStyle 可用于显示某些演示文稿：

case pageSheet

一种部分覆盖底层内容的展示风格。

你应用演示风格的方式：

func makeUIViewController(context: UIViewControllerRepresentableContext<ActivityView>) -> UIActivityViewController {
    let v = UIActivityViewController(activityItems: sharing, applicationActivities: nil)
    v.modalPresentationStyle = .pageSheet
    return v
}

可在此处找到演示文稿列表：

https://developer.apple.com/documentation/uikit/uimodalpresentationstyle

我自己还没有对它们进行全部测试，所以如果最终没有像您预期的那样工作，我提前道歉。

或者，您可以查看this answer，他们在其中提到了第三方库，这将允许您以通常呈现的方式创建半模态。

Answer 3

它并不漂亮，但你可以直接这样调用它（考虑到你的应用只有 1 个窗口）：

UIApplication.shared.windows.first?.rootViewController?.present(activityViewController, animated: true, completion: nil)

如果你得到一些警告blablabla：

警告：尝试呈现……已经在呈现……

您可以执行this to get the top most view controller 之类的操作并调用present。

Answer 4

至少在 iOS 14、Swift 5、Xcode 12.5 中，我只需将 UIActivityViewController 包装在另一个视图控制器中即可相当轻松地完成此操作。它不需要检查视图层次结构或使用任何 3rd 方库。唯一骇人听闻的部分是异步呈现视图控制器，这甚至可能不是必需的。有更多 SwiftUI 经验的人或许可以提供改进建议。

import Foundation
import SwiftUI
import UIKit

struct ActivityViewController: UIViewControllerRepresentable {
        
    @Binding var shareURL: URL?
    
    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }
    
    func makeUIViewController(context: Context) -> some UIViewController {
        let containerViewController = UIViewController()
        
        return containerViewController

    }
    
    func updateUIViewController(_ uiViewController: UIViewControllerType, context: Context) {
        guard let shareURL = shareURL, context.coordinator.presented == false else { return }
        
        context.coordinator.presented = true

        let activityViewController = UIActivityViewController(activityItems: [shareURL], applicationActivities: nil)
        activityViewController.completionWithItemsHandler = { activity, completed, returnedItems, activityError in
            self.shareURL = nil
            context.coordinator.presented = false

            if completed {
                // ...
            } else {
                // ...
            }
        }
        
        // Executing this asynchronously might not be necessary but some of my tests
        // failed because the view wasn't yet in the view hierarchy on the first pass of updateUIViewController
        //
        // There might be a better way to test for that condition in the guard statement and execute this
        // synchronously if we can be be sure updateUIViewController is invoked at least once after the view is added
        DispatchQueue.main.asyncAfter(deadline: .now()) {
            uiViewController.present(activityViewController, animated: true)
        }
    }
    
    class Coordinator: NSObject {
        let parent: ActivityViewController
        
        var presented: Bool = false
        
        init(_ parent: ActivityViewController) {
            self.parent = parent
        }
    }
    
}

struct ContentView: View {
    
    @State var shareURL: URL? = nil
    
    var body: some View {
        ZStack {
            Button(action: { shareURL = URL(string: "https://apple.com") }) {
                Text("Share")
                    .foregroundColor(.white)
                    .padding()
            }
            .background(Color.blue)
            if shareURL != nil {
                ActivityViewController(shareURL: $shareURL)
            }
        }
        .frame(width: 375, height: 812)
    }
}