Extract parameter

@implementation Greeting {
}

- (NSString *)generateGreeting{
    // This expression will be converted to
    // the method's parameter
    NSString *userName = @"Bob";
    return [NSString stringWithFormat:@"Hello %@", userName];
}

- (void)print {
    // Method's call
    NSLog(@"%@", [self generateGreeting]);
}

@end

@implementation Greeting {
}
// Method with the new parameter
- (NSString *)generateGreeting:(NSString *)userName {
    return [NSString stringWithFormat:@"Hello %@", userName];
}

- (void)print {
    // Method's call
    NSLog(@"%@", [self generateGreeting:@"Bob"]);
}

@end