格式的UIDatePicker另一個NSDate的

Question

我有一個的UIDatePicker，我用這個獲取日期：

NSDate *pickerDate = [datePickerView date]; 

我想創造一種是基於星期和時間的天將來的日期（HH ：mm：ss）從pickerDate。下面是我使用的代碼，但它生成的日期是錯誤的：

更新的代碼

 //format the uidatepicker 
     NSDate *dateSet = pickerDate; 
     NSDateFormatter *df = [[NSDateFormatter alloc] init]; 
     [df setTimeZone:[NSTimeZone localTimeZone]]; 
     [df setDateFormat:@"EEEE HH:mm:ss"]; 
     NSString *dateSetString = [df stringFromDate:dateSet]; 

     NSLog(@"repeatDateString %@",dateSetString);//prints "Tuesday 12:12:43" 

     //create a new nsdate using the new format 
     NSDateFormatter *dateFormat2 = [[NSDateFormatter alloc] init]; 
     [dateFormat2 setTimeZone:[NSTimeZone localTimeZone]]; 
     [dateFormat2 setDateFormat: @"EEEE HH:mm:ss"]; 

     NSDate *newDate = [[NSDate alloc] init]; 
     newDate = [dateFormat2 dateFromString:dateSetString]; 

     NSLog(@"new Date %@",newDate);//prints "1970-01-06 04:42:43 +0000" 

Answer 1

的問題是，你的日期字符串不包含所有的信息，從選擇器，並且沒有包含足夠的信息來重新創建日期。它錯過了日，月和年，所以當你重新創建它時，它假定你想從iOS的NSDate日曆系統開始。

您或者需要存儲從選取器（最好）收到的NSDate，或者您需要使用包含足夠信息的日期格式來創建特定的日期和時間。

編輯
基於您的評論，你只想使用從日期選擇在工作日和時間，並決定在未來與這些值的下一個日期。這裏是代碼將實現：

NSCalendar   *cal   = [NSCalendar currentCalendar]; 

NSDate    *pickerDate  = self.datePickerView.date; 
NSDateComponents *pickerComps = [cal components: NSWeekdayCalendarUnit | 
                 NSHourCalendarUnit | 
                 NSMinuteCalendarUnit | 
                 NSSecondCalendarUnit 
              fromDate:pickerDate]; 

NSDate    *currentDate = [NSDate date]; 
NSDateComponents *currentComps = [cal components: NSYearCalendarUnit | 
                 NSMonthCalendarUnit | 
                 NSWeekdayCalendarUnit | 
                 NSDayCalendarUnit | 
                 NSHourCalendarUnit | 
                 NSMinuteCalendarUnit | 
                 NSSecondCalendarUnit 
              fromDate:currentDate]; 

// Start with the current date and add/subtract the number of days needed to make it the same day of the week 
NSDateComponents *newComps  = [currentComps copy]; 
NSUInteger   weekdayDiff  = pickerComps.weekday - currentComps.weekday; 
newComps.day      = newComps.day + weekdayDiff; 
// If needed, add 7 days in order to move this date into the future 
if (newComps.day < currentComps.day) { 
    newComps.day = newComps.day + 7; 
} 

NSDate *newDate = [cal dateFromComponents:newComps]; 
if ([newDate compare:currentDate] == NSOrderedAscending) { 
    // This is true when the weekday started out the same but the time of day is earlier in the picker. 
    // Add 7 days 
    newComps.day = newComps.day + 7; 
    newDate = [cal dateFromComponents:newComps]; 
} 

NSLog(@"%@", newDate);