Iphone 使用特定时间初始化NSDate对象

我有

time

格式的

string

例如

2:00

。我想用present

date

将其初始化为

NSDate

。 我试过了

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

我无法将其与日期对象进行比较。请帮助

尝试

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];

你应该能够在那之后和日期进行比较

也许你的意思是。我想我们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];

---

您需要使用

NSCalendar

对象将

NSDateComponents

转换为

NSDate

。请参阅上的Apple文档。

要使用当前日期2初始化NSDate，您必须将NSDate与年、月和日等组件拆分，例如

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

将时间设置为2小时

weekdayComponents.hour = 2;

然后由这些组件创建一个新的NSDate

NSDate *todayAt2 = [gregorian dateFromComponents:weekdayComponents];

---

我（现在）把一些客观C答案放在一起，就有了这个辅助函数：

+ (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;
}

---

感谢您的回复。是否有办法仅使用时间组件设置此值日期需要为当前日期。是否可以仅更改使用NSDate*mydate=[NSDate date date]初始化的日期对象的时间组件；我想你的意思是这样的。是的，再次感谢你的快速回复。NSTimeInterval Diff=[lastDate TimeIntervalsIncestDate:weekdayComponents]；这是在警告我，不兼容的Objective-C类型struct-NSDateComponents需要struct-NSDate。请快速更正：应该是[weekdayComponents setSecond:30]；感谢您的回复。是否可以设置NSDate的时间组件。我可以将NSDate对象初始化为当前日期和时间。之后是否可以更改时间组件。使用相同的日历将NSDate转换为NSDate组件，然后设置时间，然后使用日历将其转换回NSDate。

+ (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;
}