iPad – Why does UIALERTCONTROLLER in iOS7 receive NIL values?

UIAlertController *view=[UIAlertController
 alertControllerWithTitle:@"Hello"
 message:nil
 preferredStyle:UIAlertControllerStyleAlert];< br />
 [self presentViewController:view animated:NO completion:nil];

Why UIAlertController in iOS7 needs to be presented but receives nil value when working on iOS8 is good, I may know Is that because iOS7 does not support the UIAlertController class?

UIAlertController *view=[UIAlertController
 alertControllerWithTitle:@"Hello"
 message:nil
 preferredStyle:UIAlertControllerStyleAlert];< br />
 [self presentViewController:view animated:NO completion:nil];

These classes are only available for iOS8 and later. See class reference