ios - AlamofireImage 磁盘缓存不工作

Question

我想使用 AlamofireImage 从 url 下载图像，然后将其缓存在设备磁盘空间中。我阅读了几篇关于此的文章，发现 AlamofireImage 在 ImageDownloader 的帮助下支持这一点。类(class)。给出了最有趣的信息in this SO answer

所以我尝试为 ImageDownloader 设置一个自定义的 NSURLCache，这样它就可以将图像直接缓存到磁盘上。我通过将内存容量设置为 0 来做到这一点。然后我使用这个自定义 ImageDownloader 下载图像。我为磁盘路径指定的文件夹是在磁盘上创建的，但不幸的是它仍然是空的，并且图像没有以任何方式缓存。

** 编辑:** 请务必注意，缓存响应并未保存在缓存目录中的文件夹中，而是保存在该文件夹旁边的数据库文件中。

谁能告诉我我做错了什么？非常感谢阅读!

func diskImageDownloader(diskSpaceMB: Int = 100) -> ImageDownloader {

    let diskCapacity = diskSpaceMB * 1024 * 1024
    let diskCache = NSURLCache(memoryCapacity: 0, diskCapacity: diskCapacity, diskPath: "alamofireimage_disk_cache")
    let configuration = NSURLSessionConfiguration.defaultSessionConfiguration()
    configuration.URLCache = diskCache
    let downloader = ImageDownloader(configuration: configuration)
    UIImageView.af_sharedImageDownloader = downloader

    return downloader
}

func getProfileImage(atURL url: String, onComplete: SRServiceResponse<UIImage> -> Void) {
    guard let imageURL = NSURL(string: url) else
    {
        // TODO: Fail here
        return
    }

    let request = NSURLRequest(URL: imageURL)

    let imageDownloader = self.diskImageDownloader()

    imageDownloader.downloadImage(URLRequest: request) { (response) in
        switch response.result
        {
        case .Success(let image):
            // Do something
        case .Failure(let error):
            // Do something
        }
    }
}

Answer 1

我这样做不是为了代表。只是为了节省您使用编译器的时间。

在Swift 3.0

class DiskCache: URLCache {


  private let constSecondsToKeepOnDisk = numDaysToKeep*24*60*60 // numDaysToKeep is your own constant or hard-coded value

  override func storeCachedResponse(_ cachedResponse: CachedURLResponse, for request: URLRequest) {

    var customCachedResponse = cachedResponse
    // Set custom Cache-Control for Image-Response
    let response = cachedResponse.response as! HTTPURLResponse

    if let contentType = response.allHeaderFields["Content-Type"] as? String,
        var newHeaders = response.allHeaderFields as? [String: String], contentType.contains("image") {
        newHeaders["Cache-Control"] = "public, max-age=\(constSecondsToKeepOnDisk)"
        if let url = response.url, let newResponse = HTTPURLResponse(url: url, statusCode: response.statusCode, httpVersion: "HTTP/1.1", headerFields: newHeaders) {
            customCachedResponse = CachedURLResponse(response: newResponse, data: cachedResponse.data, userInfo: cachedResponse.userInfo, storagePolicy: cachedResponse.storagePolicy)
        }
    }
    super.storeCachedResponse(customCachedResponse, for: request)
  }
}