I have a file paylines.txt added inside the folder named TextFiles which resides inside the Resources folder of my iOS project in Xcod
paylines.txt
TextFiles
Resources
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"];