I know this question has already been asked for various times, but none of the solutions worked for me.
How do I hide the network activity indicator in the iOS status-bar?
The most websites tell you to use the following code, but the indicator still appears in the status bar.
[[UIApplication sharedApplication] setNetworkActivityIndicatorVisible: NO];
It's possible that some other code (static library / open source you're using) is setting the visibility to YES.
I would set a symbolic breakpoint at -[UIApplication setNetworkActivityIndicatorVisible:] and see which piece of code is responsible.
Follow these instructions to set a symbolic breakpoint.