accessing a file using [NSBundle mainBundle] pathForResource: ofType:inDirectory:

I was also having the same problem. The Solution i found is ( in xcode 4.x):

Go to : Target -> "Build Phases" -> "copy bundle Resources" Then add that particular file here. If that file is already added , delete it and add it again.

clean the project and RUN. It works. :)

well i found out the mistake i was committing i was adding a group to the project instead of adding real directory for more instructions

Try this, it's working for me.

NSString *str = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"paylines.txt"];  

For simulator

NSURL *rtfUrl = [[NSBundle mainBundle] URLForResource:@"paylines" withExtension:@".txt"];