If you use add file add some files in your project. You can access them like this:
    NSError *error;
    NSString *filepath = [[NSBundle mainBundle] pathForResource:@"hello" ofType:@"txt"];  // I add __hello.txt__ into my project.
    NSString *filecontent = [NSString stringWithContentsOfFile:filepath encoding:NSUTF8StringEncoding error:&error];
    NSLog(@" content: %@", filecontent);
    And If you want read file line by line. You can do this:
     // this array's length is the number of lines.
     NSArray *fileContent = [[NSString stringWithContentsOfFile:filepath encoding:NSUTF8StringEncoding error:&error] componentsSeparatedByString:@"\n"];