計算兩個日期之間的日間時間和夜間時間

Question

由於「夜間時間」定義爲晚上8點到7點59分，我試圖計算兩個日期之間的白天時間和夜間時間量AM，以及上午8點到下午7點59分的「白天時間」。我將與當前時間戳比較的過去日期總是比現在少於24小時。

我該怎麼做？

Answer 1

當您開始處理夏令時等時，您很快就會變得非常複雜，因此您確實需要使用當前日曆並使用日曆/日期函數來計算時差。例如，如果時鐘在凌晨3點向前移動1小時，那麼根據您在時間更改當天的定義，應該有11個小時的「夜間」（而不是12個小時）。

我還沒有徹底測試此代碼，但它應該是相當接近：

// 8:00:00 AM in seconds 
static const NSTimeInterval daytimeStart = 28800; 
// 8:00:00 PM in seconds 
static const NSTimeInterval daytimeStop = 72000; 

// Convert date to a "time" which is the number of seconds since midnight, NOT considering time changes 
- (NSTimeInterval)getTimeForDate:(NSDate *)date { 
    NSCalendar *cal = [NSCalendar currentCalendar]; 

    NSDateComponents *dateComps = [cal components:NSHourCalendarUnit | 
                NSMinuteCalendarUnit | 
                NSSecondCalendarUnit 
             fromDate:date]; 
    NSTimeInterval time = dateComps.hour * 3600 + dateComps.minute * 60 + dateComps.second; 
    return time; 
} 

// Set the time to the specified hour and minutes/seconds to 0 
- (NSDate *)dateBySettingTimeToBeginningOfHour:(NSUInteger)hour ofDate:(NSDate *)date { 
    NSCalendar *cal = [NSCalendar currentCalendar]; 

    NSDateComponents *dateComps = [cal components:NSYearCalendarUnit | 
            NSMonthCalendarUnit | 
            NSDayCalendarUnit | 
            NSHourCalendarUnit | 
            NSMinuteCalendarUnit | 
            NSSecondCalendarUnit 
             fromDate:date]; 
    [dateComps setHour:hour]; 
    [dateComps setMinute:0]; 
    [dateComps setSecond:0]; 
    NSDate *newDate = [cal dateFromComponents:dateComps]; 
    return newDate; 
} 

// Add one day to the current date 
- (NSDate *)dateByAddingOneDayToDate:(NSDate *)date { 
    NSCalendar *cal = [NSCalendar currentCalendar]; 

    NSDateComponents *dateComps = [cal components:NSYearCalendarUnit | 
            NSMonthCalendarUnit | 
            NSDayCalendarUnit | 
            NSHourCalendarUnit | 
            NSMinuteCalendarUnit | 
            NSSecondCalendarUnit 
             fromDate:date]; 
    [dateComps setDay:[dateComps day] + 1]; 
    NSDate *newDate = [cal dateFromComponents:dateComps]; 
    return newDate; 
} 

// Check to see if it is daytime 
- (BOOL)isDayForDate:(NSDate *)date { 
    NSTimeInterval time = [self getTimeForDate:date]; 
    if (time >= daytimeStart) { 
     if (time < daytimeStop) { 
      return YES; 
     } 
    } 

    // Default 
    return NO; 
} 

// Check to see if it is night 
- (BOOL)isNightForDate:(NSDate *)date { 
    return ![self isDayForDate:date]; 
} 

// When do we transition from day to night or night to day next? 
- (NSDate *)dateForNextTransitionForDate:(NSDate *)date { 
    NSTimeInterval time = [self getTimeForDate:date]; 
    if (time < daytimeStart) { 
     return [self dateBySettingTimeToBeginningOfHour:8 ofDate:date]; 
    } 

    if (time < daytimeStop) { 
     return [self dateBySettingTimeToBeginningOfHour:20 ofDate:date]; 
    } 

    // Tomorrow morning 
    NSDate *newDate = [self dateByAddingOneDayToDate:date]; 
    newDate = [self dateBySettingTimeToBeginningOfHour:8 ofDate:newDate]; 
    return newDate; 
} 

- (NSTimeInterval)nightTimeFromDate:(NSDate *)startingDate toDate:(NSDate *)laterDate { 
    if ([startingDate compare:laterDate] != NSOrderedAscending) { 
     return 0; 
    } 

    NSTimeInterval nightTime = 0; 
    NSDate *now     = laterDate; 
    NSDate *transitionDate  = startingDate; 
    NSDate *loopDate   = startingDate; 
    BOOL isNight    = [self isNightForDate:startingDate]; 

    do { 
     transitionDate = [self dateForNextTransitionForDate:transitionDate]; 
     if ([transitionDate compare:now] == NSOrderedDescending) { 
      transitionDate = now; 
     } 

     if (isNight) { 
      nightTime = nightTime + [transitionDate timeIntervalSinceDate:loopDate]; 
     } 

     loopDate = transitionDate; 
     isNight = !isNight; 
    } while ([transitionDate compare:now] != NSOrderedSame); 

    return nightTime; 
} 

- (NSTimeInterval)dayTimeFromDate:(NSDate *)startingDate toDate:(NSDate *)laterDate { 
    if ([startingDate compare:laterDate] != NSOrderedAscending) { 
     return 0; 
    } 

    NSTimeInterval diff = [laterDate timeIntervalSinceDate:startingDate]; 
    diff = diff - [self nightTimeFromDate:startingDate toDate:laterDate]; 
    return diff; 
} 

// Example usage: 
NSDate *now = [NSDate date]; 
NSDate *date = [NSDate dateWithTimeInterval:-82800 sinceDate:now]; 

NSLog(@"%f", [self nightTimeFromDate:date toDate:now]); 
NSLog(@"%f", [self dayTimeFromDate:date toDate:now]); 

// Results are 43200.000000 and 39600.000000 right now in the middle of the day. 

Answer 2

白天=（（今天最後一天）之間的天數* 12）+（＃今天白天）+

夜間=（（排名（對最後一天，白天＃）今天最後一天）* 12）+夜間小時（＃今天）+（在最後一天＃的夜間時段）

編輯

int dthours = 0, nthours = 0; 

dthours += ternary with a calculation of 24 - starthour logic for daytime 
nthours += ternary with a calculation of 24 - starthour logic for nighttime 
dthours += ternary with a calculation of endhour logic for daytime 
nthours += ternary with a calculation of endhour logic for nighttime 

邏輯爲明天的夜間時段之間的天看起來像：

nthours += (endhour - 4 > 0) ? ((endhour - 16 > 0) ? endhour - 12 : 4) : endhour;