iOS nsurlsession completehandler default call Quque

Attention

[[Nsurlsession sharedsession] datataskwithrequest:request completionhandler:^ (NSData *data, NSURLResponse *response, Nserror *error)

This method uses the default configuration, then Completehanlder does not execute in Mainqueue, see the following official documents:

A queue for scheduling the delegate calls and completion handlers. If nil , the session creates a serial operation queue for performing all delegate method calls and completion handle R calls.

The result is that Completehandler is not executing the main thread (100%? ), but executes in a child thread.

iOS nsurlsession completehandler default call Quque