我的应用看起来像这样。App Image 我的桌子上有歌曲，可以下载它们以及将其暂停和恢复。但是我对暂停和恢复有问题。例如，我单击下载Track01，然后暂停10％的下载。然后，我单击下载Track02，并暂停30％的下载。现在，我单击恢复下载Track01，他从30％恢复，但没有恢复10％。 Track02的任务替换Track01的任务。如何为每个音轨分别制定任务？我的下载代码如下：
class DownloadTracks: NSObject,URLSessionDownloadDelegate, URLSessionTaskDelegate, URLSessionDelegate {
var task : URLSessionDownloadTask!
let configuration = URLSessionConfiguration.default
let operationQueue = OperationQueue.main
var session : URLSession!
var downloadTaskID : Int!
var progress : Float = 0.0
func downloadTask(url : URL) {
session = URLSession.init(configuration: configuration, delegate: self, delegateQueue: operationQueue)
task = session.downloadTask(with: url)
task.resume()
print("go download")
}
func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
print("1111")
}
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
let documentaryDirectoryURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
let destenationURL = documentaryDirectoryURL.appendingPathComponent(downloadTask.description + ".mp3")
print(destenationURL)
do {
try FileManager.default.moveItem(at: location, to: destenationURL)
}
catch let error as NSError {
print(error.localizedDescription)
}
}
func pauseDownload() {
task.suspend()
}
func resumeDownload() {
task.resume()
}
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
progress = Float (totalBytesWritten) / Float(totalBytesExpectedToWrite)
print(progress)
}
}