There are plenty of ways to pass data between the controllers, but the simplest one here would be for you to add an NSString property in the header file of your radioPlayer, and then just pass the data to it, for example:
UIStoryboard *sb = [UIStoryboard storyboardWithName:@"Main_iPhone" bundle:nil];
UIViewController *vc = [sb instantiateViewControllerWithIdentifier:@"radioPlayer"];
vc.myStringData = @"Data that needs to be passed.";
[self presentViewController:vc animated:NO completion:nil];