自我是必要的你希望一个对象发送消息，好吧， self 。通过getter / setter访问属性有时也是有益的，在这种情况下，您还需要使用 self ，如 self.propertyname 或 self.propertyname = value 。 （这些不等于 propertyname 或 propertyname = value 。

self is necessary if you wish for an object to send messages to, well, itself. It is also occasionally beneficial to access properties through getters/setters, in which case you'll also need to use self, as in self.propertyname or self.propertyname = value. (These are not equivalent to propertyname or propertyname = value.