Question

我有一个名为visitDate的coredata属性

我想使用单独的选择器相互独立地设置日期和时间。

我意识到当我设置时间时，我需要获取visitDate的现有日期，月份和年份，但只能从NSDatePicker设置时间。

相反，当我设置日期时，我需要抓住visitDate的现有小时，分钟和秒，并且只设置日期。

我想我要问的是如何通过使用另一个NSDate实例的select元素来创建NSDate实例？

Answer 1

使用NSDateComponents。另请参阅Date and Time Programming Guide。

Answer 2

可能需要一些不必要的代码，但这就是我的工作。

if (editing == Date) {

    if ([visit valueForKey:@"visitDate"] == nil) {
        [visit setValue:datePicker.date forKey:@"visitDate"];
    }
    else {
        NSDateFormatter *hourFormat = [[NSDateFormatter alloc] init];
        [hourFormat setDateFormat:@"HH"];
        NSString *hourString = [hourFormat stringFromDate:[visit valueForKey:@"visitDate"]];

        NSDateFormatter *minuteFormat = [[NSDateFormatter alloc] init];
        [minuteFormat setDateFormat:@"mm"];
        NSString *minuteString = [minuteFormat stringFromDate:[visit valueForKey:@"visitDate"]];

        NSDateFormatter *dayFormat = [[NSDateFormatter alloc] init];
        [dayFormat setDateFormat:@"dd"];
        NSString *dayString = [dayFormat stringFromDate:datePicker.date];

        NSDateFormatter *monthFormat = [[NSDateFormatter alloc] init];
        [monthFormat setDateFormat:@"MM"];
        NSString *monthString = [monthFormat stringFromDate:datePicker.date];

        NSDateFormatter *yearFormat = [[NSDateFormatter alloc] init];
        [yearFormat setDateFormat:@"YYYY"];
        NSString *yearString = [yearFormat stringFromDate:datePicker.date];

        NSDateComponents *components = [[NSDateComponents alloc] init];
        [components setMinute:[minuteString intValue]];
        [components setHour:[hourString intValue]];
        [components setDay:[dayString intValue]]; //Set Day
        [components setMonth:[monthString intValue]]; //Set Month
        [components setYear:[yearString intValue]]; //Set Year
        NSCalendar *gregorian = [[NSCalendar alloc]
                                 initWithCalendarIdentifier:NSGregorianCalendar];
        NSDate *date = [gregorian dateFromComponents:components];

        [visit setValue:date forKey:@"visitDate"];
    }
    [visitTableView reloadData];
    NSLog(@"Date Saved as %@", visit.visitDate);

}
else if (editing == Time) {

    if ([visit valueForKey:@"visitDate"] == nil) {
        [visit setValue:datePicker.date forKey:@"visitDate"];
    }
    else {
        NSDateFormatter *hourFormat = [[NSDateFormatter alloc] init];
        [hourFormat setDateFormat:@"HH"];
        NSString *hourString = [hourFormat stringFromDate:datePicker.date];

        NSDateFormatter *minuteFormat = [[NSDateFormatter alloc] init];
        [minuteFormat setDateFormat:@"mm"];
        NSString *minuteString = [minuteFormat stringFromDate:datePicker.date];

        NSDateFormatter *dayFormat = [[NSDateFormatter alloc] init];
        [dayFormat setDateFormat:@"dd"];
        NSString *dayString = [dayFormat stringFromDate:[visit valueForKey:@"visitDate"]];

        NSDateFormatter *monthFormat = [[NSDateFormatter alloc] init];
        [monthFormat setDateFormat:@"MM"];
        NSString *monthString = [monthFormat stringFromDate:[visit valueForKey:@"visitDate"]];

        NSDateFormatter *yearFormat = [[NSDateFormatter alloc] init];
        [yearFormat setDateFormat:@"YYYY"];
        NSString *yearString = [yearFormat stringFromDate:[visit valueForKey:@"visitDate"]];

        NSDateComponents *components = [[NSDateComponents alloc] init];

        [components setMinute:[minuteString intValue]];
        [components setHour:[hourString intValue]];
        [components setDay:[dayString intValue]]; //Set Day
        [components setMonth:[monthString intValue]]; //Set Month
        [components setYear:[yearString intValue]]; //Set Year
        NSCalendar *gregorian = [[NSCalendar alloc]
                                 initWithCalendarIdentifier:NSGregorianCalendar];
        NSDate *date = [gregorian dateFromComponents:components];

        [visit setValue:date forKey:@"visitDate"];
    }
    [visitTableView reloadData];
    NSLog(@"Date Saved as %@", visit.visitDate);

}

Answer 3

如果您正在使用UIDatePicker（您提到过NSDatePicker），则可以设置UIDatePicker.datePickerMode和UIDatePicker.date。如果两个选择器同时显示在屏幕上，您可以在UIControlEventValueChanged事件上复制日期。如果没有，当您显示选择器时可能更容易设置UIDatePicker.date，并在隐藏选择器时将其复制到visitDate。

CoreData - 如何相互独立地设置日期和时间？

3 个答案: