?
?獲取加方法 ?: ?class_getClassMethod ??
Method ?method1 = class_getClassMethod ( [Person class],@selector(run) );
?獲取減方法 ? : ?class_getInstanceMethod ? ?
Method method2 = class_getInstanceMethod ( [Person class],@selector(sleep) );
交換方法 :? method_exchangeImplementations( 方法1,方法2 );
method_exchangeImplementations(method1, method2);