Obtains a preference value for the specified key and application.
- iOS 2.0+
- macOS 10.0+
- UIKit for Mac 13.0+Beta
- tvOS 9.0+
- watchOS 2.0+
- Core Foundation
The preference key whose value to obtain.
The preference data for the specified key and application. If no value was located, returns
NULL. Ownership follows the The Create Rule.
Note that values returned from this function are immutable, even if you have recently set the value using a mutable object.