What is __NSArrayI and __NSArrayM?
__NSArrayI(or M) cause "unrecognized selector" error.
How to convert to NSArray?
I did test to parse json, twitter api.
http://api.twitter.com/1/followers/ids.json?cursor=-1&screen_name=twitterapi
==> works fine. parsed object is NSCFDictionary class. (This dictionary contains __NSArrayM class)
http://api.twitter.com/1/statuses/user_timeline.json?&screen_name=twitterapi
==> error. parsed object is __NSArrayM class.
__NSArrayI is a code-word for an immutable array - that is, a "regular" NSArray which you cannot change.
__NSArrayM is a code-word for a mutable array - that is, NSMutableArray. In NSMutableArray, you can add and remove items.