The index number of the destructive button.
- iOS 2.0–8.3Deprecated
- Mac Catalyst 13.0–13.0Deprecated
Button indices start at
0. The default value of this property is normally
-1, which indicates that no destructive button has been set. However, a destructive button may be created and set automatically by the
init method. If you use that method to create a destructive button, you should not change the value of this property.