我已使用配置下载会话
NSURLSessionConfiguration *backgroundConfiguration = [NSURLSessionConfiguration backgroundSessionConfiguration:sessionIdentifier];
[backgroundConfiguration setAllowsCellularAccess:YES];
self.backgroundSession = [NSURLSession sessionWithConfiguration:backgroundConfiguration
delegate:self
delegateQueue:[NSOperationQueue mainQueue]];
并使用它激活它
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[hostComponents URL]]; [request setAllowsCellularAccess:YES]; NSMutableData *bodyMutableData = [NSMutableData data]; [bodyMutableData appendData:[params dataUsingEncoding:NSUTF8StringEncoding]]; [request setHTTPMethod:@"POST"]; [request setHTTPBody:[bodyMutableData copy]]; _downloadTask = [self.backgroundSession downloadTaskWithRequest:request]; [self.downloadTask resume];
现在一切都可以正常工作,只有当我通过Wifi连接或超过蜂窝,但iPhone连接到xCode的电缆,如果我断开iPhone,并通过蜂窝接收推送通知代码停止在[self.downloadTask resume];线不调用URL.
处理这些操作的类是NSURLSessionDataDelegate,NSURLSessionDownloadDelegate,NSURLSessionTaskDelegate等实现：
- (void)URLSession:(NSURLSession *)session didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition,NSURLCredential *))completionHandler - (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite - (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didResumeAtOffset:(int64_t)fileOffset expectedTotalBytes:(int64_t)expectedTotalBytes - (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(NSURL *)location
我尝试在[self.downloadTask resume]之后插入一个UILocalNotification(现在显示为’now)的调试行,但在5分钟后调用,并指出self.downloadTask.state被“暂停”
什么是这个奇怪的行为？
解决方法
@H_404_22@ NSURLSessionConfiguration类参考文档在这里：说：自由财产：
Discussion@H_502_30@
When this flag is set,transfers are more likely to occur when plugged
into power and on Wi-Fi. This value is false by default.This property is used only if a session’s configuration object was
originally constructed by calling the backgroundSessionConfiguration:
method,and only for tasks started while the app is in the foreground.
If a task is started while the app is in the background,that task is
treated as though discretionary were true,regardless of the actual
value of this property.@H_502_30@ For sessions created based on other
configurations,this property is ignored.
这似乎意味着如果下载在后台启动,操作系统总是有权决定是否和何时进行下载.在完成这些任务之前,操作系统总是等待WiFi连接.
我的经验支持这个猜想.我发现,当设备处于蜂窝状态时,我可以发送几个下载通知.他们仍然卡住当我将设备切换到wifi时,他们都会通过.
