使用 nsdate 比较两个日期

发布于 2024-12-12 09:18:36 字数 466 浏览 0 评论 0原文

在我的应用程序中，我必须比较两次：当前（即 12:44）和考虑到我尝试过：

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"hh:mm"];
NSDate *neededDate = [[NSDate alloc] init];
neededDate = [dateFormatter dateFromString:@"14:45"];
if ([neededDate compare:[NSDate date]] == NSOrderedAscending) {
NSLog(@"yes");
} else NSLog(@"no");
[neededDate release];
[dateFormatter release];

但任何时候我启动它，NSLog 都会说“不”。请指出我哪里错了。先感谢您。

原文

In my app I have to compare two times: current (which is 12:44) and given I tried:

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"hh:mm"];
NSDate *neededDate = [[NSDate alloc] init];
neededDate = [dateFormatter dateFromString:@"14:45"];
if ([neededDate compare:[NSDate date]] == NSOrderedAscending) {
NSLog(@"yes");
} else NSLog(@"no");
[neededDate release];
[dateFormatter release];

But any time I launch it, NSLog says "no". Please, suggest where I' m wrong. Thank you in advance.

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成熟的代价 2024-12-19 09:18:36

因为您的 neededDate 将等于 “1970/01/01 14:45”。

您需要设置正确的年份和日期。

例如，您可以使用下一种方法获取当前年份、月份：

NSDateComponents *components = [[NSCalendar currentCalendar] components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit fromDate:[NSDate date]];
NSLog(@"Current year: %d", components.year);
NSLog(@"Current month: %d", components.month);
NSLog(@"Current day: %d", components.day);

Because your neededDate will be equal to "1970/01/01 14:45".

You need to set correct year and date.

You can get current year, month and say, for example, using next approach:

NSDateComponents *components = [[NSCalendar currentCalendar] components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit fromDate:[NSDate date]];
NSLog(@"Current year: %d", components.year);
NSLog(@"Current month: %d", components.month);
NSLog(@"Current day: %d", components.day);

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旧话新听 2024-12-19 09:18:36

我认为问题在这里：

[dateFormatter setDateFormat:@"hh:mm"];

应该是：

[dateFormatter setDateFormat:@"HH:mm"];

因为现在对于“14:45”它返回（空）日期

（这是对之前答案的补充：）

I think the problem is here:

[dateFormatter setDateFormat:@"hh:mm"];

should be:

[dateFormatter setDateFormat:@"HH:mm"];

because now for "14:45" it returns (null) date

(this is additionally to previous answer :)

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等风也等你 2024-12-19 09:18:36

这意味着在您的情况下，needDate 始终高于当前日期。
这可能是因为您以 24 小时格式存储 48 小时字符串。
还将字符串更改为 HH:mm

，验证您存储在 NeededDate 中的值。

这是

NSDate *neededDate = [[NSDate date] dateByAddingTimeInterval:5];
    if ([neededDate compare:[NSDate date]] == NSOrderedAscending) {
        NSLog(@"asc");
    } else {
        NSLog(@"dec");
    }

本例中的一个小示例，将打印 dec。

it means that in your case, neededDate is always higher than the current date.
this is probably because you store a 48 hour string in a 24 hour format.
change the string to HH:mm

also, verify the value you store in neededDate.

here's a small example

NSDate *neededDate = [[NSDate date] dateByAddingTimeInterval:5];
    if ([neededDate compare:[NSDate date]] == NSOrderedAscending) {
        NSLog(@"asc");
    } else {
        NSLog(@"dec");
    }

in this case, dec will be printed.

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