使用Mantle过程中，当用到枚举类型表示状态时，新添加枚举值时

+ (NSValueTransformer *)reviewStatusJSONTransformer {
    NSDictionary *status = @{
        @"pending": @(ZYSeviewStating),
        @"rejected": @(ZYSeviewStatusFail),
        @"authed": @(ZYSeviewStatusPass)
    };
    return [MTLValueTransformer transformerUsingForwardBlock:^id(id value, BOOL *success, NSError *__autoreleasing *error) {
        return status[value] ?: @(ZYSeviewUnknown);
    }];
}