我有一个上传(视频)数据到服务器的方法,它看起来像这样:
static func upload(video data:Data, named name:String, parameters:[String:Any], toUrl url:URL, progress:@escaping (Double)->Void, completion:@escaping(Bool)->Void){
manager = Alamofire.SessionManager(configuration: URLSessionConfiguration.background("com.app.backgroundtransfer")
manager.upload(multipartFormData: { (multipartFormData) in
multipartFormData.append(data, withName: "filedata", fileName: name, mimeType: "video/quicktime")
for key in parameters.keys{
if let val = parameters[key] as? String{
multipartFormData.append(val.data(using: .utf8, allowLossyConversion: false)!, withName: key)
}
}
}, to: url) {
(encodingResult) in
switch encodingResult {
case .success(let upload, _, _):
upload.uploadProgress(closure: { (uploadProgress) in
progress(uploadProgress.fractionCompleted)
//this one stops getting called
})
upload.responseJSON { response in
// but this one gets called at the end.
}
case .failure(let encodingError):
print(encodingError)
}
}
}
所以问题是,当我从后台返回时(在上传过程中),我不能正确地更新UI。
这个进度回调(后台返回后)为什么会停止工作?
发布于 2019-03-05 08:41:07
Alamofire与后台会话并不真正兼容。因为它是一个基于闭包的API,不能在应用程序进入后台时持久化,所以当应用程序处于前台时,您的进程闭包不会被重新连接。建议您直接使用URLSession
或者使用后台任务接口,而不要使用后台会话。
发布于 2019-03-06 21:54:32
所以我所做的,是使用后台任务(完全没有Alamofire的情况下也是这样做的)并且它起作用了。如下所示:
var backgroundTask: UIBackgroundTaskIdentifier = .invalid
func registerBackgroundTask() {
backgroundTask = UIApplication.shared.beginBackgroundTask {
self.endBackgroundTask()
}
assert(backgroundTask != .invalid)
}
func endBackgroundTask() {
print("Background task ended.")
UIApplication.shared.endBackgroundTask(backgroundTask)
backgroundTask = .invalid
}
APIClient.manager = Alamofire.SessionManager(configuration: URLSessionConfiguration.background(withIdentifier: "com.app.backgroundtransfer"))
self.registerBackgroundTask()
APIClient.upload(video: video, named: videoDetailsModel.videoURL!.lastPathComponent, parameters: self.uploadParameters, toUrl: url, progress: {[weak self] (percentage) in
guard let `self` = self else {return}
print("Progress \(percentage)")
self.progressBar.progress = CGFloat(percentage)
}, completion: { [weak self] (success) in
guard let `self` = self else {return}
if(success){
print("Video successfully uploaded")
self.endBackgroundTask()
self.progressBar.progress = 1.0
}else{
print("Video upload was not successfull")
}
})
现在进度回调可以正常工作了,您仍然可以使用Alamofire来打包多部分数据,就像我使用它一样,或者出于任何原因使用它。
https://stackoverflow.com/questions/54983913
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