获取所有值

typedef NS_ENUM(NSInteger, Season) {
    SeasonSummer,
    SeasonFall,
    SeasonWinter,
    SeasonSpring,
    SeasonCount
};

//C enums are not iterable: the count
//sentinel bounds the loop
for (NSInteger s = SeasonSummer;
    s < SeasonCount; s++) {
    //0, 1, 2, 3
}