UIAlertController，如果是ios8，否则就是UIAlertView

I want to conform to the UIAlertController used in iOS 8 since UIAlertView is now deprecated. Is there a way that I can use this without breaking support for iOS 7? Is there some kind of if condition I can do to check for iOS 8 otherwise do something else for iOS 7 support?I want to conform to the UIAlertController used