我想知道你是否看到这个或可能有一些想法,为什么我看到我的代码中的以下行为:我有NSURLsession与背景配置。当程序在前台运行时,我会启动定期下载任务,并且一切正常。当我模拟backgroundfetch(在xcode中)时,我的任务得到一个空值(尽管请求和会话不为空)。当然在这种情况下,我的会话委托永远不会被解雇以执行完成处理程序。如果我模拟后续的后台提取,它们都会在后面工作。在这一点上,如果我将该应用程序带到模拟器的前台,并且模拟了另一个后台存取,症状会遍布全部。我在我的appdelegate类中使用了这段代码。下载任务是空的第一个请求时,当在后台IOS IOS
非常感谢您的帮助。
- (NSURLSession *)FlickrSession
{
if(!_FlickrSession)
{
NSLog(@"setting new FlickrSession");
NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration backgroundSessionConfiguration:FLICKR_SESSION];
configuration.allowsCellularAccess = NO;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
_FlickrSession = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];
_FlickrSession.sessionDescription = FLICKR_SESSION;
NSLog(@" new self is %@", _FlickrSession);
NSLog(@"queue in session %@", dispatch_get_current_queue());
});
}
return _FlickrSession;
}
-(void) startFlickrFetch
{
// initialize session config and the background session
[self.FlickrSession getTasksWithCompletionHandler:^(NSArray *dataTasks, NSArray *uploadTasks, NSArray *downloadTasks)
{
if(![downloadTasks count])
{
NSLog(@"new downloadtask session %@", self.FlickrSession.sessionDescription);
NSURLRequest *request = [NSURLRequest requestWithURL:[FlickrFetcher URLforRecentGeoreferencedPhotos]];
// NSURLSessionDownloadTask *task = [self.FlickrSession downloadTaskWithURL:[FlickrFetcher URLforRecentGeoreferencedPhotos]];
NSURLSessionDownloadTask *task = [self.FlickrSession downloadTaskWithRequest:request];
task.taskDescription = FLICKR_DOWNLOAD_TASK;
NSLog(@"new request %@", request);
NSLog(@"new downloadtask %@", task);
[task resume];
//task?[task resume]:[self fireBackgroungFetchCompletionHandler];;
//[self fireBackgroungFetchCompletionHandler];
NSLog(@"queue in task %@", dispatch_get_current_queue());
}
else
{
NSLog(@"resuming old downloadtask %d", [downloadTasks count]);
for(NSURLSessionDownloadTask *task in dataTasks) [task resume];
}
}];
NSLog(@"queue outside the block %@", dispatch_get_current_queue());
}
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions: (NSDictionary *)launchOptions
{
// Override point for customization after application launch.
// open the file, if there is no managedContext. this is the case wjere the application was launched directly by user
// it did not come from the bckground state;
//need to enable background fetch
[[UIApplication sharedApplication] setMinimumBackgroundFetchInterval:UIApplicationBackgroundFetchIntervalMinimum];
//[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(documentChangedState) name:UIDocumentStateChangedNotification object: self.document];
NSLog(@"in application didfinishlaunching");
[self openDatabaseFile];
[self startFlickrFetch];
return YES;
}
-(void) application:(UIApplication *)application performFetchWithCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler
{
self.backgroundFetchCompletionHandler = completionHandler;
if(self.document.documentState == UIDocumentStateNormal)
{
//[self openDatabaseFile];
NSLog(@"in performFetchWithCompletionHandler");
[self startFlickrFetch];
}
}
- (void) application:(UIApplication *)application handleEventsForBackgroundURLSession:(NSString *)identifier completionHandler:(void (^)())completionHandler
{
self.completionhandler = completionHandler;
NSLog(@"handle event for backgroundURLsession***********");
}
我注意到了类似的行为。特别是,如果我在创建任务之前中断并跳过它,我会得到零。如果我在创建任务后中断,则返回任务。这是在模拟器中。 – Felix
我遇到了同样的问题(在设备上测试过),相同的症状。当在''application:performFetchWithCompletionHandler:''中运行''downloadTaskWithRequest:''时,你会得到零。 – desudesudesu
我也看到这发生在一个真实的设备上。 (iOS 7.0.3) – TJez