SwiftUI中点击Button如何直接调用UIAction.captureTextFromCamera提取实况文本

核心逻辑：UIAction.captureTextFromCamera 确实要求必须关联到Menu才能正常触发，我们可以通过添加完全隐藏的Menu、点击按钮时主动触发Menu内的动作来实现需求，无需用户手动点击Menu选项。

步骤1：创建文本接收响应器 #

首先创建承接实况文本返回结果的响应器类，遵循系统要求的UIKeyInput协议：

import UIKit

class CameraTextCaptureResponder: UIResponder, UIKeyInput {
    var onTextCaptured: (String) -> Void
    
    init(onTextCaptured: @escaping (String) -> Void) {
        self.onTextCaptured = onTextCaptured
        super.init()
    }
    
    var hasText: Bool { true }
    
    func insertText(_ text: String) {
        onTextCaptured(text)
    }
    
    func deleteBackward() {}
    
    override func canPerformAction(_ action: Selector, withSender sender: Any?) -> Bool {
        if action == #selector(captureTextFromCamera(_:)) {
            return true
        }
        return super.canPerformAction(action, withSender: sender)
    }
    
    @objc func captureTextFromCamera(_ sender: Any?) {}
}

步骤2：实现SwiftUI视图逻辑 #

通过隐藏Menu+按钮主动触发的方式实现直接调用：

import SwiftUI

struct LiveTextDemoView: View {
    @State private var text = ""
    @State private var triggerHiddenMenu = false
    // 初始化响应器，接收返回的文本
    private let captureResponder = CameraTextCaptureResponder { newText in
        DispatchQueue.main.async {
            text = newText
        }
    }
    
    var body: some View {
        VStack(spacing: 30) {
            Text(text)
                .padding()
                .border(.gray.opacity(0.3), cornerRadius: 8)
            
            Button {
                // 点击按钮直接触发隐藏Menu内的动作
                triggerHiddenMenu = true
            } label: {
                Label("提取实况文本", systemImage: "camera.viewfinder")
                    .padding()
                    .background(.blue)
                    .foregroundColor(.white)
                    .cornerRadius(8)
            }
            // 挂载完全隐藏的Menu
            .background {
                Menu(isPresented: $triggerHiddenMenu) {
                    Button(action: {
                        let action = UIAction.captureTextFromCamera(responder: captureResponder, identifier: nil)
                        action.perform(with: nil)
                    }) {
                        EmptyView()
                    }
                } label: {
                    EmptyView()
                }
                .menuStyle(.borderlessButton)
                .menuIndicator(.hidden)
                .opacity(0)
                .allowsHitTesting(false)
            }
        }
        .padding()
    }
}

注意事项 #

• 该功能仅支持iOS 16及以上系统
• 必须在项目Info.plist中添加NSCameraUsageDescription键，填写相机使用权限说明，否则调用时会直接崩溃
• 捕获到的文本回调默认在非主线程返回，更新UI时需要手动切到主线程

内容的提问来源于stack exchange，提问作者Underthestars-zhy