I'd like to upload lots of files to server. for instance, the user taken images more than 50 when not reachable on network and hit send button. Then i should upload them when reachable on network. iOS doesn't allows to add session task with large size post request when not reachable on network. so i've tried a chained tasks. but it's takes very long time to wakeup next task.
There is no limitation for requests in iOS. You can send data with arbitrary length to a server. But, for large data you should avoid loading the complete data into memory. Instead you should setting HTTPBodyStream in NSMutableURLRequest or a file (e.g. uploadTaskWithRequest:fromFile:completionHandler:).