It seems that when you enqueue too many tasks (say, hundreds) on a background NSURLSession
, it doesn't work well. How can you keep the number of enqueued tasks at a small fixed number, say 10?
It seems that when you enqueue too many tasks (say, hundreds) on a background NSURLSession
, it doesn't work well. How can you keep the number of enqueued tasks at a small fixed number, say 10?
In the class that is responsible for enqueueing tasks, have a ivar to track the active tasks, e.g.
// In MySessionWrapper.m
@interface MySessionWrapper () {
NSMutableSet *activeTaskIds;
}
@end
When you enqueue a task, you add its ID to that set:
[activeTaskIds addObject:@([task taskIdentifier])]
When you get a didComplete
callback, you remove the ID, and if the number of active tasks falls below your
target, you add more tasks:
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error
{
// other stuff
[activeTaskIds removeObject:@([task taskIdentifier])]
if ([activeTaskIds count] < NUMBER) {
// add more tasks
}
}
This system is working for me now.