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Accepted
BriteKnight
Asked: 2025-01-14 11:15:08 +0800 CST

如何在 UIViewController 和 Swift UI View 之间共享图像数据？

  • 772

在我苦苦寻找使用 AVCapture 实现保存图像的相机功能的方法时，我找到了一个使用 UIKit 的很棒的 YouTube 教程。由于我想在完全基于 SwiftUI 构建的应用中实现此功能，因此我只需在包含 UIKit 教程中的代码的 ViewController 中创建 HostedViewController 结构即可。这种托管在单独情况下运行良好（现在仍然运行良好），但我的应用要求将捕获的图像传递给 SwiftUI 视图（仅默认的 ContentView 文件）。我该怎么做？我最初的想法是将图像作为绑定从 SwiftUI 视图传递给 ViewController，但我很难实现这一点。

这是我的 ContentView 文件：

import AVFoundation
import UIKit

struct ContentView: View {
    
    var body: some View {
        
        ZStack {
            
            Color.purple
            
            HostedViewController()
                .ignoresSafeArea()
            
        }
        
    }
}

#Preview {
    ContentView()
}

以下是我的 ViewController 文件的相关部分：

class ViewController: UIViewController {
    
    // capture session
    var session: AVCaptureSession?
    
    // photo output
    let output = AVCapturePhotoOutput()
    
    // video preview
    let previewLayer = AVCaptureVideoPreviewLayer()
    
    //The rest is a bunch of AVCapture stuff that isn't relevant to my question
    
    @objc private func didTapTakePhoto() {
        output.capturePhoto(with: AVCapturePhotoSettings(), delegate: self)
    }

}

extension ViewController: AVCapturePhotoCaptureDelegate {
    func photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photo: AVCapturePhoto, error: Error?) {
        guard let data = photo.fileDataRepresentation() else {
            return
        }

        //saves the image, this is the data I want to pass to the ContentView
        let image = UIImage(data: data)
        
        //displays the image
        session?.stopRunning()
        
        let imageView = UIImageView(image: image)
        imageView.contentMode = .scaleAspectFill
        imageView.frame = view.bounds
        view.addSubview(imageView)
    }
}

struct HostedViewController: UIViewControllerRepresentable {
    
    func makeUIViewController(context: Context) -> UIViewController {
        return ViewController()
    }
    
    func updateUIViewController(_ uiViewController: UIViewController, context: Context) {
    }
    
    typealias UIViewControllerType = UIViewController
}

我需要对此进行哪些具体的更改以便能够从 ContentView 文件中的 ViewController 文件访问图像常量？

提前致谢。

swift

1 个回答

  1. Best Answer

    从我的角度来看，您可以尝试这种方法：Binding在 ViewController 和 ContentView 之间创建一个属性：

    struct ContentView: View {
    @State private var selectedImage: UIImage?
    
    var body: some View {
        ZStack {
            if let selectedImage {
                //TODO: - do something with the image that captured from AVCapturePhotoCaptureDelegate
            }

            ...
            HostedViewController(image: $selectedImage)
        }
    }
}

struct HostedViewController: UIViewControllerRepresentable {
    @Binding var image: UIImage?
    
    func makeUIViewController(context: Context) -> ViewController {
        let vc = ViewController()
        vc.selectedImage = $image
        return vc
    }
}

    最后就是selectedImage在 内进行设置photoOutput(_ didFinishProcessingPhoto:error:)，这样图像就会自动同步ContentView到 触发if let selectedImage。

    class ViewController: UIViewController, AVCapturePhotoCaptureDelegate {
    var selectedImage: Binding<UIImage?> = .constant(nil)

    func photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photo: AVCapturePhoto, error: Error?) {
        ...
        selectedImage.wrappedValue = image
        ...
    }
}

    另一种方法是创建Coordinator然后HostedViewController重新分配AVCapturePhotoCaptureDelegate给它的协调器，例如：

    class Coordinator: NSObject, AVCapturePhotoCaptureDelegate {
    @Binding var selectedImage: UIImage?
    init(selectedImage: Binding<UIImage?>) {
        _selectedImage = selectedImage
    }

    func photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photo: AVCapturePhoto, error: Error?) {
        ...
        selectedImage = image
    }
}
    • 1

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