如何使用AlamofireImage ProgressHandler

Question

我很难弄清楚如何准确地定义ProgressHandler参数。typealias被定义为public typealias ProgressHandler = (bytesSent: Int64, totalBytesSent: Int64, totalExpectedBytes: Int64) -> Void，更多信息可以在这里找到https://github.com/Alamofire/AlamofireImage/pull/91

let URLRequest = NSURLRequest(URL: NSURL(string: "https://httpbin.org/image/jpeg")!)
    ImageDownloader().downloadImages(URLRequests: [URLRequest], filter: nil,
 progress: (init progress here), progressQueue: dispatch_get_main_queue(), completion: {
            _ in
        })

不是复制品！所引用的答案/问题是导致实现 https://stackoverflow.com/a/33503205/5222077的这个特性的原因。

Answer 1

用Swift定义它，就像定义任何闭包一样。您可以为捕获的参数指定任何您想要的名称，也可以使用_给出任何名称，但是您需要有3个。

ImageDownloader().downloadImage(URLRequest: "http://httpbin.org/image/png", progress: { (bytesRead, totalBytesRead, totalExpectedBytesToRead) in
    print("Read:\(bytesRead), Total Read: \(totalBytesRead), Expected: \(totalExpectedBytesToRead)")
})