以下代码使用UIGestureRecognizer:
UIGestureRecognizer *gestureRecog = [[UIGestureRecognizer alloc]
initWithTarget:self
action:@selector(handletap:)];
[self.view addGestureRecognizer:gestureRecog];
可以实际编译运行。我认为抽象类不能被实例化?