計算兩個日期之間差異的問題

Question

我需要在幾分鍾內計算兩天之間的差異。

NSDate *now = [[NSDate alloc] init];

NSDateFormatter *outputFormatter = [[NSDateFormatter alloc] init];
    [outputFormatter setLocale:[[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"]];
    [outputFormatter setDateFormat:@"dd/MM/yyyy hh:mm:ss a"];

    NSString* dateStringFromDatabase = @"01/01/1900 11:00:00 AM";

    NSDate* dateFromString = [outputFormatter dateFromString:dateStringFromDatabase];

NSString* a = [outputFormatter stringFromDate:now];
    NSDate* b = [outputFormatter dateFromString:a];

    NSCalendar *gregorian = [[NSCalendar alloc]initWithCalendarIdentifier:NSGregorianCalendar];

    unsigned int unitFlags = NSHourCalendarUnit | NSMinuteCalendarUnit | NSDayCalendarUnit | NSMonthCalendarUnit;

    NSDateComponents *components = [gregorian components:unitFlags fromDate:dateFromString
                                                  toDate:b options:0];

    int hours = [components hour];
    int minutes = [components minute];

    self.lblResult.text = [NSString stringWithFormat:@"%i:%i", hours, minutes];

但是我有以下幾個問題：目前的時間我得到：

2012-10-21 07:37:09 +0000 // wrong it's two hours late

當我嘗試將@"01/01/1900 11:00:00 AM"投射到NSDate我得到了

1900-01-01 10:00:00 +0000 // also two hours late

Answer 1

您需要設置-dateStyle而不是時間樣式，因為該字符串中還包含日期。

編輯 - -

您現在需要將-dateFormat更改為dd/MM/yyyy HH:mm:ss a

Answer 2

嘗試這個..................

如果您在String中有日期，則使用@"dd/MM/yyyy hh:mm:ss a"將其轉換為日期

NSDate *startDate = ...;
NSDate *endDate = ...;

現在日期比較

// Date Comparision
NSCalendar *gregorian = [[NSCalendar alloc]initWithCalendarIdentifier:NSGregorianCalendar];

unsigned int unitFlags = NSHourCalendarUnit | NSMinuteCalendarUnit | NSDayCalendarUnit | NSMonthCalendarUnit;

NSDateComponents *components = [gregorian components:unitFlags fromDate:LastDate
                                              toDate:CuurentDate options:0];

獲得兩個日期之間的差異

int months = [components month];
int days = [components day];
int hours = [components hour];
int minutes = [components minute];

Answer 3

我希望這有幫助

    NSString *dtString = @"1900-01-01T11:00:00";
    dtString = [dtString stringByReplacingOccurrencesOfString:@"T" withString:@" "];
    NSDate *today = [NSDate date];
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"YYYY-MM-dd HH:mm:ss"];
    NSString *currentTime = [dateFormatter stringFromDate:today];
    NSDate *toTimeDate = [dateFormatter dateFromString:dtString];
    NSString *toTime = [dateFormatter stringFromDate:toTimeDate];