IOS switch-case Statement requires expression of integer type ('NSString *__strong' invalid)
1.switch参数类型switch参数类型要求是integertype,准确来讲,是可以转换成integer的类型,这包括所有的C基本数据类型((signed/unsigned)char,(short/longsigned/unsigned)int,float,double,longlong,bool(C++/objective-c)),还有枚举类型,但是不包括字符串、结构体、联合体、对象、函数