IPHONE MinutesToMidnight 出现的编译错误，已找到解决方法

-(void)updateLabel { 
NSDate* now = [NSDate date]; 
int hour = 23 - [[now dateWithCalendarFormat:nil timeZone:nil] hourOfDay]; 
int min = 59 - [[now dateWithCalendarFormat:nil timeZone:nil] minuteOfHour]; 
int sec = 59 - [[now dateWithCalendarFormat:nil timeZone:nil] secondOfMinute]; 
countdownLabel.text = [NSString stringWithFormat:@"%02d:%02d:%02d", hour, min,sec]; 
}  

修改为： 

-(void)updateLabel { 
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar]; 
unsigned unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit| NSMinuteCalendarUnit |NSSecondCalendarUnit; 
NSDate *date = [NSDate date]; 
NSDateComponents *comps = [gregorian components:unitFlags fromDate:date]; 
int hour = 23 - [comps hour]; 
int min = 59 - [comps minute]; 
int sec = 59 - [comps second];    
countdownLabel.text = [NSString stringWithFormat:@"%02d:%02d:%02d", hour, min,sec]; 
}