存储时间值并进行比较

Question

我正在尝试获取时间点，然后进行比较。我已经想出了如何比较它们，但我正在尝试创建 NSDate 对象来代表一天中的时间，这会造成一些麻烦。我使用了NSDateFromComponents 并使用了setHour: 和setMinute: 函数，但它没有成功修改对象。它还需要自动将日期的其他组成部分设置为当前时间和日期。

比较对象：

static bool DateIsBetween(NSDate *beginDate, NSDate *date, NSDate *endDate) {
    return [date timeIntervalSince1970] > [beginDate timeIntervalSince1970] && [date    timeIntervalSince1970] < [endDate timeIntervalSince1970];
}

创建日期对象：

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

[calendar setTimeZone:[NSTimeZone timeZoneWithName:@"EST"]];
NSDateComponents *weekdayComponents = [calendar components:NSWeekdayCalendarUnit fromDate:todayDate];

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

[genericTimeComponents setHour:5];
[genericTimeComponents setMinute:0];
[genericTimeComponents setDay:weekdayComponents.day];
[genericTimeComponents setYear:weekdayComponents.year];
[genericTimeComponents setMonth:weekdayComponents.month];


NSDateComponents *secondComps = [[NSDateComponents alloc]init];
[secondComps setHour:7];
[secondComps setMinute:0];
[secondComps setDay:weekdayComponents.day];
[secondComps setYear:weekdayComponents.year];
[secondComps setEra:weekdayComponents.era];
[secondComps setMonth:weekdayComponents.month];

Answer 1

确保在您的日期比较函数中使用括号（只是为了清楚起见；从逻辑上讲，它应该可以正常工作）：

 static bool DateIsBetween(NSDate *beginDate, NSDate *date, NSDate *endDate) {
    return (([date timeIntervalSince1970] > [beginDate timeIntervalSince1970]) && ([date    timeIntervalSince1970] < [endDate timeIntervalSince1970]));
}

对于这种情况，最好为 NSDate 类创建一个类别并编写一个 Objective-c 方法。

对于其余部分，我尝试了以下代码，它对我有用：

NSDate * now = [NSDate date];

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

[gregorian setTimeZone:[NSTimeZone localTimeZone]];

NSDateComponents *genericTimeComponents = [gregorian components:(NSWeekdayCalendarUnit |NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit |NSYearCalendarUnit|NSMonthCalendarUnit|NSEraCalendarUnit)
                                                      fromDate:now];

[genericTimeComponents setHour:5];
[genericTimeComponents setMinute:0];

//  Quick Check 
NSLog(@"GTC=%@", genericTimeComponents);