objc警告:"从指针目标类型中丢弃限定符"

编译时:

char *str = [[NSString stringWithFormat:@"%i days and %i hours", days, hours] UTF8String];

我收到这个警告:

initialization discards qualifiers from pointer target type

我怎么摆脱它？

你缺少的资格赛是const.-UTF8String返回一个const char *,所以str也应该声明const char *.