I am building my first iOS app.
I have got the backend code done, but I am struggling with the Objective-C part of it.
I have a signup / login page.
But
Since you're trying to login to your own API, you don't want setAuthorization stuff. That's for basic HTTP auth. Instead you want to use getPath:parameters:success:failure or the postPath version, depending on if your backend is expecting HTTP GET or HTTP POST.
Pass your userid / password in the parameters argument. You should set parameterEncoding to be the correct format. You're probably using HTTP Forms url encoding, or JSON. Whatever your backend expects.