如下面的方法的一部分,我可以問類型的recorgnier對象UISwipeGestureRecognizer *previousLocationInView,澄清需要
- (void) handleSwipeFrom:(UISwipeGestureRecognizer*)recognizer
關於其當前位置
CGPoint currentLocation = [recognizer locationInView:self];
據documentation,我應該也能得到
CGPoint previousLocation = [recognizer previousLocationInView:self];
然而,這種方法不是可用。請問我錯過了什麼?