Runtime

 

 获取加方法  :  class_getClassMethod   

Method  method1 = class_getClassMethod ( [Person class],@selector(run) );

 获取减方法   :  class_getInstanceMethod    

Method method2 = class_getInstanceMethod ( [Person class],@selector(sleep) );

交换方法 :  method_exchangeImplementations( 方法1,方法2 );

method_exchangeImplementations(method1, method2);