Swift iOS应用中AVAsset仅存入数组一个对象的问题排查

我用Swift开发iOS应用的照片和视频功能，图片功能正常，images和uiimages数组能正确填充。但视频有问题：即便imageIndex已经更新，videos和media数组始终只保存一个视频，新视频会覆盖旧的。视频的逻辑和图片完全一致，图片存入media（[AnyObject]）数组没问题，视频却不行，求原因。

相关代码 #

主视图代码 #

@State var images = [Image?](repeating: nil, count: 6)
@State var uiimages = [UIImage?](repeating: nil, count: 6)
@State var videos = [AVAsset?](repeating: nil, count: 6)
@State var media = [AnyObject?](repeating: nil, count: 6)

...

CaptureImageView(isShown: $showCaptureImageView, uiimage: $uiimages[imageIndex], image: $images[imageIndex], video: $videos[imageIndex], amedia: $media[imageIndex], camera: camera)
    .onAppear {
        self.disableButtons = true
    }
    .onDisappear {
        var nonNil:Int = 0
        for media in media {
            if media != nil {
                nonNil += 1
            }
        }
        self.nonNilImages = nonNil
        self.imageIndex = nonNil
        self.disableButtons = false
        print("-------")
        print("imageIndex: \(imageIndex)")
        print(videos)
        print(media)
    }

CaptureImageView 实现 #

import SwiftUI
import AVFoundation

struct CaptureImageView {
    
    @Binding var isShown: Bool
    @Binding var uiimage: UIImage?
    @Binding var image: Image?
    @Binding var video: AVAsset?
    @Binding var amedia: AnyObject?
    
    var camera: Bool
    
    func makeCoordinator() -> Coordinator {
        return Coordinator(isShown: $isShown, image: $image, uiimage: $uiimage, video: $video, amedia: $amedia)
    }
}
extension CaptureImageView: UIViewControllerRepresentable {
    func makeUIViewController(context: UIViewControllerRepresentableContext<CaptureImageView>) -> UIImagePickerController {
        let picker = UIImagePickerController()
        picker.delegate = context.coordinator
        if camera {
            
            if let mediaTypes = UIImagePickerController.availableMediaTypes(for: .camera) {
                picker.mediaTypes = mediaTypes
            }
            
            picker.sourceType = .camera
        }
        return picker
    }
    
    func updateUIViewController(_ uiViewController: UIImagePickerController,
                                context: UIViewControllerRepresentableContext<CaptureImageView>) {
        
    }
}

Coordinator 实现 #

import SwiftUI
import AVFoundation
class Coordinator: NSObject, UINavigationControllerDelegate, UIImagePickerControllerDelegate {
  @Binding var isCoordinatorShown: Bool
  @Binding var uiimageInCoordinator: UIImage?
  @Binding var imageInCoordinator: Image?
  @Binding var videoInCoordinator: AVAsset?
  @Binding var mediaInCoordinator: AnyObject?
    
  init(isShown: Binding<Bool>, image: Binding<Image?>, uiimage: Binding<UIImage?>, video: Binding<AVAsset?>, amedia: Binding<AnyObject?>) {
    _isCoordinatorShown = isShown
    _uiimageInCoordinator = uiimage
    _imageInCoordinator = image
    _videoInCoordinator = video
    _mediaInCoordinator = amedia
  }
    func imagePickerController(_ picker: UIImagePickerController,
                didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        if let videoURL = info[UIImagePickerController.InfoKey.mediaURL] as? URL {
            let asset = AVAsset(url: videoURL)
            print(asset)
            videoInCoordinator = AVAsset(url: videoURL)
            mediaInCoordinator = AVAsset(url: videoURL)
        } else if let unwrapImage = info[UIImagePickerController.InfoKey.originalImage] as? UIImage {
            // handle image pick
            uiimageInCoordinator = unwrapImage
            imageInCoordinator = Image(uiImage: unwrapImage)
            mediaInCoordinator = unwrapImage
        }
        isCoordinatorShown = false
    }
  func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
     isCoordinatorShown = false
  }
}

问题分析与解决方案 #

核心问题1：临时视频文件被系统回收 #

UIImagePickerController返回的视频URL指向系统临时文件，控制器消失后该文件可能被系统删除，导致数组中存储的AVAsset变成无效引用，看起来像是被覆盖。而图片直接返回UIImage对象，数据保存在内存中不会丢失。

核心问题2：AnyObject数组的状态追踪问题 #

media数组类型为[AnyObject?]，SwiftUI对抽象类型的状态变化追踪不够敏感，相比之下具体类型（如UIImage）的绑定更新更可靠。

次要问题：循环变量名冲突 #

onDisappear中的循环变量media与数组名media重名，虽语法合法但易导致逻辑混淆，可能引发计数错误。

具体修复步骤 #

1. 复制视频到应用沙盒，避免临时文件被删除
   修改Coordinator中视频处理代码，将视频复制到应用Documents目录确保持久化：

func imagePickerController(_ picker: UIImagePickerController,
            didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
    if let videoURL = info[UIImagePickerController.InfoKey.mediaURL] as? URL {
        // 获取应用Documents目录
        guard let documentsDir = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else {
            isCoordinatorShown = false
            return
        }
        // 生成唯一文件名避免重复
        let fileName = UUID().uuidString + ".mov"
        let destinationURL = documentsDir.appendingPathComponent(fileName)
        
        do {
            // 复制视频到沙盒
            try FileManager.default.copyItem(at: videoURL, to: destinationURL)
            let asset = AVAsset(url: destinationURL)
            videoInCoordinator = asset
            mediaInCoordinator = asset
        } catch {
            print("视频复制失败：\(error.localizedDescription)")
        }
    } else if let unwrapImage = info[UIImagePickerController.InfoKey.originalImage] as? UIImage {
        uiimageInCoordinator = unwrapImage
        imageInCoordinator = Image(uiImage: unwrapImage)
        mediaInCoordinator = unwrapImage
    }
    isCoordinatorShown = false
}

2. 替换AnyObject数组为自定义枚举类型
   定义枚举统一管理图片和视频，让SwiftUI更准确追踪状态变化：

// 自定义媒体类型枚举
enum MediaItem {
    case image(UIImage)
    case video(AVAsset)
}

// 更新State变量类型
@State var media = [MediaItem?](repeating: nil, count: 6)

同时修改CaptureImageView和Coordinator的绑定类型：

// CaptureImageView中修改amedia的绑定类型
@Binding var amedia: MediaItem?

// Coordinator中修改mediaInCoordinator的绑定类型
@Binding var mediaInCoordinator: MediaItem?

// Coordinator的初始化方法对应修改
init(isShown: Binding<Bool>, image: Binding<Image?>, uiimage: Binding<UIImage?>, video: Binding<AVAsset?>, amedia: Binding<MediaItem?>) {
    _isCoordinatorShown = isShown
    _uiimageInCoordinator = uiimage
    _imageInCoordinator = image
    _videoInCoordinator = video
    _mediaInCoordinator = amedia
}

// 修改didFinishPickingMediaWithInfo中的赋值逻辑
if let videoURL = info[UIImagePickerController.InfoKey.mediaURL] as? URL {
    // ... 沙盒复制代码 ...
    let asset = AVAsset(url: destinationURL)
    videoInCoordinator = asset
    mediaInCoordinator = .video(asset)
} else if let unwrapImage = info[UIImagePickerController.InfoKey.originalImage] as? UIImage {
    uiimageInCoordinator = unwrapImage
    imageInCoordinator = Image(uiImage: unwrapImage)
    mediaInCoordinator = .image(unwrapImage)
}

3. 修复循环变量名冲突
   修改onDisappear中的循环变量名，避免与数组名重名：

.onDisappear {
    var nonNil:Int = 0
    // 将循环变量改为element，避免与media数组重名
    for element in media {
        if element != nil {
            nonNil += 1
        }
    }
    self.nonNilImages = nonNil
    self.imageIndex = nonNil
    self.disableButtons = false
    print("-------")
    print("imageIndex: \(imageIndex)")
    print(videos)
    print(media)
}

内容的提问来源于stack exchange，提问作者Joseph