iOS判断是12小时还是24小时制

//获取系统是24小时制或者12小时制

    NSString *formatStringForHours = [NSDateFormatter dateFormatFromTemplate:@"j" options:0 locale:[NSLocale currentLocale]];

    NSRange containsA = [formatStringForHours rangeOfString:@"a"];

    BOOL hasAMPM = containsA.location != NSNotFound;

//hasAMPM==TURE为12小时制，否则为24小时制