Safe Casting in Objective-C with macros.

ASTSafeCast.m

#define ASTCastInline(valueIn, ObjectType) \
    ([valueIn isKindOfClass:[Type class]] ? (Type *)valueIn : nil)

#define ASTCast(valueIn, ObjectType, valueOut) \
    ObjectType *valueOut = ([valueIn isKindOfClass:[ObjectType class]] ? (ObjectType *)valueIn : nil);

usage.m

- (IBAction)somethingHappened:(id)sender {
    ASTCast(sender, UIButton, button);
    ASTCast(sender, UIGestureRecognizer, recognizer);
    if (button) {
        NSLog(@"Invoked by button: %@", button);
    } else if (recognizer) {
        NSLog(@"Invoked by gesture recognizer: %@", recognizer);
    } else {
        NSLog(@"Invoked by unknown sender: %@", sender);
    }
}