Because each object can have its own version of a method, an Objective-C statement can achieve a variety of results, not by varying the message but by varying the object that receives the message.

例如，一个矩形对象，可以有实例变量来标识矩形在图上的位置以及他的宽度和高度。

youdao

Because each object can have its own version of a method, an Objective-C statement can achieve a variety of results, not by varying the message but by varying the object that receives the message.

例如，一个矩形对象，可以有实例变量来标识矩形在图上的位置以及他的宽度和高度。

youdao