oc 无中生有添加协议（使已有函数符合协议）

class_addProtocol([UIButton class],@protocol(UIButtonExport));

@protocol UIButtonExport <JSExport>

- (void)setTitle:(NSString *)title forState:(UIControlState)state;

- (void)setBackgroundImage:(UIImage *)image forState:(UIControlState)state;

@end