使用特定时间初始化 NSDate 对象

Question

我有 string 格式的 time，例如 2:00。我想将其初始化为带有当前日期的NSDate。 我尝试这样做，

   NSDateComponents *comps = [[NSDateComponents alloc] init];
   [comps setHour:2];

但无法将其与日期对象进行比较。请帮忙

Answer 1

尝试一下，

NSDateComponents *comps = [[NSDateComponents alloc] init];
[comps setDay:6];
[comps setMonth:5];
[comps setYear:2004];

NSCalendar *gregorian = [[NSCalendar alloc]
    initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *date = [gregorian dateFromComponents:comps];

您应该能够与之后的日期进行比较。

也许你的意思是这样的。我认为将使用今天的日期进行设置，然后您可以从中创建 NSDateComponents 并设置时间值。

NSDate *today = [NSDate date];
NSCalendar *gregorian = [[NSCalendar alloc]
                         initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *weekdayComponents =
                    [gregorian components:(NSDayCalendarUnit | NSWeekdayCalendarUnit) fromDate:today];
[weekdayComponents setHour:12];
[weekdayComponents setMinute:10];
[weekdayComponents setSecond:30];

Answer 2

要使用当前日期 2 初始化 NSDate，您必须将 NSDate 与组件年、月和日分开，例如

NSDate *today = [NSDate date];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *weekdayComponents = [gregorian
                                       components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit)
                                       fromDate:today];

将小时设置为 2

weekdayComponents.hour = 2;

然后通过这些组件创建一个新的 NSDate

NSDate *todayAt2 = [gregorian dateFromComponents:weekdayComponents];

Answer 3

您需要使用 NSCalendar 对象将 NSDateComponents 转换为 NSDate。请参阅 Apple 的文档 从组件创建日期。

Answer 4

  func initializeDateWithTime(date:NSDate,hrs:Int,minutes:Int) -> NSDate{
    let today = date
     let gregorian:NSCalendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)!
     let dateComponents = gregorian.components([.Year, .Month, .Day], fromDate: today)

     dateComponents.hour = hrs;
     dateComponents.minute = minute;


     let todayAtX = gregorian.dateFromComponents(dateComponents)
     return todayAtX!
}

Answer 5

只是将 Objective C 的一些答案汇集在一起​​，我（现在）有了这个辅助函数：

+ (NSDate*)dateForTodayAtHour:(NSUInteger)hour andMinutes:(NSUInteger)minutes {
    NSDate* today = [NSDate date];
    NSCalendar* gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
    NSDateComponents* weekdayComponents = [gregorian components:(NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear) fromDate:today];
    [weekdayComponents setHour:hour];
    [weekdayComponents setMinute:minutes];
    [weekdayComponents setSecond:0];
    NSDate* result = [gregorian dateFromComponents:weekdayComponents];
    return result;
}