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新手在这里尝试修改苹果提供的“日期单元”示例代码以用于学习目的，并且在格式化日期方面遇到了真正的麻烦。我有一个 tableView，在第 1 行 (datePickerModeDateAndTime)、第 2 行 (pickerModeDate)、第 3 行 (pickerModeTime) 中有三个单独的 datePicker。现在，我正在努力从记录的第一个选择器（dateAndTime）中获取值，以便以后可以访问它。我以“2013 年 9 月 20 日，下午 12:12”的形式在 tableView 单元格的详细信息中显示了所选日期。我正在尝试获取详细信息的值并将“NSDate 日期”和所选时间之间的差异写入 DD:HH:MM:SS 剩余的应用程序文档目录中，以便我可以设置一个计时器另一个视图开始倒计时到选定的日期/时间并在 UILabel 中显示计时器计数。I have the log writing the date as '2013-09-20 18:12:33 +0000' when the picker is initially loaded to the screen but after the components change the log reads '0:00:00:-10'. 所以我已经部分完成了我想要的，但没有成功地从中获得正确的日期。谢谢！

if(self.datePickerIndexPath.row == 1){
                targetedDatePicker.datePickerMode = UIDatePickerModeDateAndTime;
                self.dateFormatter = [[NSDateFormatter alloc] init];
                [self.dateFormatter setDateStyle:NSDateFormatterMediumStyle];
                [self.dateFormatter setTimeStyle:NSDateFormatterShortStyle];

                NSDate *selected = [NSDate dateWithTimeIntervalSince1970:[self.pickerView.date timeIntervalSince1970] - 1];
                self.deadlineCounter = [self.formatter stringFromDate:selected];

                NSLog(@"selected is: %@", selected);

                NSDate *todaysDate = [NSDate date];

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

                NSUInteger unitFlags = NSDayCalendarUnit | NSMinuteCalendarUnit | NSHourCalendarUnit | NSSecondCalendarUnit;
                NSDateComponents *dateComparisonComponents = [gregorian components:unitFlags
                                                                          fromDate:todaysDate
                                                                            toDate:selected
                                                                           options:NSWrapCalendarComponents];
                NSInteger days = [dateComparisonComponents day];
                NSInteger hours = [dateComparisonComponents hour];
                NSInteger minutes = [dateComparisonComponents minute];
                NSInteger seconds = [dateComparisonComponents second];

                self.DeadlineCounter = [NSString stringWithFormat:@"%ld:%02ld:%02ld:%02ld",
                                        (long)days,
                                        (long)hours,
                                        (long)minutes,
                                        (long)seconds];
                NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
                NSString *deadline = [NSString stringWithFormat:@"%@/deadline.txt", documentsDirectory];
                NSInteger success = [NSKeyedArchiver archiveRootObject:selected toFile:deadline];
                NSLog(@"success is: %d",success);
                NSLog(@"deadline.txt was written successfully with these contents %@,", self.deadlineCounter);

                targetedDatePicker.minimumDate = [NSDate date];
                targetedDatePicker.maximumDate = [todaysDate dateByAddingTimeInterval:604800];
            }

基本上，如果用户从日期选择器中选择“2013 年 9 月 25 日，下午 2:25”，我想编写字符串以便可以创建倒数计时器，显示在另一个视图中，并设置为关闭并选择日期和时间。（我已经得到要在正确的控制器上写入和读取的日期，并且 timerLabel 以“0:00:00:00”的形式显示日期，但这是错误的数字）

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1 回答 1

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试试这个代码：

 NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
 [dateFormatter setDateFormat:@"MMM' 'dd','yyyy' 'HH':'mm' a"];
 [dateFormatter setAMSymbol:@"AM"];
 [dateFormatter setPMSymbol:@"PM"];

 NSDate *dateFromString = [dateFormatter dateFromString:uploadDate];
于 2013-09-20T19:10:44.243 回答