SwiftUI从相册选GIF：保留动画、获取时长及完整上传问题

1. 显示带动画的GIF #

SwiftUI原生Image不支持动画GIF，需通过UIViewRepresentable包装UIKit的UIImageView实现：

struct AnimatedGIFView: UIViewRepresentable {
    let data: Data
    
    func makeUIView(context: Context) -> UIImageView {
        let imageView = UIImageView()
        if let gifImage = UIImage.gif(data: data) {
            imageView.image = gifImage
            imageView.contentMode = .scaleAspectFit
            imageView.startAnimating()
        }
        return imageView
    }
    
    func updateUIView(_ uiView: UIImageView, context: Context) {}
}

extension UIImage {
    static func gif(data: Data) -> UIImage? {
        guard let source = CGImageSourceCreateWithData(data as CFData, nil) else {
            return nil
        }
        let count = CGImageSourceGetCount(source)
        var images = [UIImage]()
        var delays = [Double]()
        
        for i in 0..<count {
            guard let cgImage = CGImageSourceCreateImageAtIndex(source, i, nil) else { continue }
            images.append(UIImage(cgImage: cgImage))
            
            guard let properties = CGImageSourceCopyPropertiesAtIndex(source, i, nil) as? [String: Any],
                  let gifProperties = properties[kCGImagePropertyGIFDictionary as String] as? [String: Any],
                  let delayTime = gifProperties[kCGImagePropertyGIFDelayTime as String] as? Double else {
                delays.append(0.1)
                continue
            }
            delays.append(delayTime)
        }
        return UIImage.animatedImage(with: images, duration: delays.reduce(0, +))
    }
}

使用示例：

// 假设已获取GIF原始data
AnimatedGIFView(data: gifData)
    .frame(width: 200, height: 200)

2. 获取GIF总时长 #

封装解析函数直接从原始数据计算时长：

func getGIFDuration(from data: Data) -> Double {
    guard let source = CGImageSourceCreateWithData(data as CFData, nil) else {
        return 0
    }
    let count = CGImageSourceGetCount(source)
    var totalDuration = 0.0
    
    for i in 0..<count {
        guard let properties = CGImageSourceCopyPropertiesAtIndex(source, i, nil) as? [String: Any],
              let gifProperties = properties[kCGImagePropertyGIFDictionary as String] as? [String: Any],
              let delayTime = gifProperties[kCGImagePropertyGIFDelayTime as String] as? Double else {
            totalDuration += 0.1
            continue
        }
        totalDuration += delayTime
    }
    return totalDuration
}

调用示例：

else if mimeType == "image/gif" {
    let duration = getGIFDuration(from: data)
    print("GIF时长：\(duration)秒")
    // 后续逻辑...
}

3. 解决GIF上传末尾缺失问题 #

问题根源是将原始GIF数据转成UIImage时丢失了格式信息，直接使用PhotosPicker获取的原始data上传即可保留完整数据：

修改你的GIF分支代码：

else if mimeType == "image/gif" {
    let gifDuration = getGIFDuration(from: data)
    print("GIF时长：\(gifDuration)")
    
    // 直接使用原始数据，跳过UIImage转换
    uploadData = data
    
    // 存储data用于AnimatedGIFView显示
    self.gifData = data
    
    do {
        try await uploadToServer(mime: mimeType)
    } catch {
        print(error)
    }
}

在视图中替换原Image(uiImage: image!)：

if let gifData = gifData {
    AnimatedGIFView(data: gifData)
        .scaledToFit()
} else if let image = image {
    Image(uiImage: image)
        .resizable()
        .scaledToFit()
}

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