0

我正在比较两个日期，但是当我将两个日期输入到字符串变量中时，它可以工作，但是当我将这些值传递给数据比较方法时，它为什么不起作用？

这是我使用的代码吗？

NSString *dateString =@"2013-05-12 22:10:02";
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
// this is imporant - we set our input date format to match our input string
// if format doesn't match you'll get nil from your string, so be careful
[dateFormatter setDateFormat:@"yyyy-MM-dd HH:MM:SS"];
NSDate *dateFromString = [[NSDate alloc] init];
// voila!
dateFromString = [dateFormatter dateFromString:dateString];



NSString *dateString1 = @"2013-03-04 07:59:08";
NSDateFormatter *dateFormatter1 = [[NSDateFormatter alloc] init];
// this is imporant - we set our input date format to match our input string
// if format doesn't match you'll get nil from your string, so be careful
[dateFormatter1 setDateFormat:@"yyyy-MM-dd HH:MM:SS"];
NSDate *dateFromString1 = [[NSDate alloc] init];
// voila!
dateFromString1 = [dateFormatter dateFromString:dateString1];

if ([dateFromString compare:dateFromString1] == NSOrderedDescending)
{
    NSLog(@"1 is later than 2");

} else if ([dateFromString compare:dateFromString1] == NSOrderedAscending)
{
    NSLog(@"1 is earlier than 2");

} else
{
    NSLog(@"dates are the same");

}

**当我将日期（nsstring 格式）传递给方法时 

(int)compareDate:(NSString *)date1:(NSString *)date2

在那个方法中我写了上面的比较代码所以我调用这个方法就像

[self compareDate:date1:date2]

而且我总是得到“日期相同”的价值？？？？当我手动输入日期时，我会得到准确的答案？为什么会这样？**

4

2 回答 2

2

用下面的代码替换您的代码。“mm”格式表示分钟，“MM”表示月份。并使用“ss”几秒钟而不是“SS”。阅读苹果文档以获取有关日期格式化程序的详细信息。

 NSString *dateString =@"2013-05-12 22:10:02";
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    // this is imporant - we set our input date format to match our input string
    // if format doesn't match you'll get nil from your string, so be careful
    [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSDate *dateFromString = [[NSDate alloc] init];
    // voila!
    dateFromString = [dateFormatter dateFromString:dateString];



    NSString *dateString1 = @"2013-03-04 07:59:08";
    NSDateFormatter *dateFormatter1 = [[NSDateFormatter alloc] init];
    // this is imporant - we set our input date format to match our input string
    // if format doesn't match you'll get nil from your string, so be careful
    [dateFormatter1 setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSDate *dateFromString1 = [[NSDate alloc] init];
    // voila!
    dateFromString1 = [dateFormatter dateFromString:dateString1];

    if ([dateFromString compare:dateFromString1] == NSOrderedDescending)
    {
        NSLog(@"1 is later than 2");

    } else if ([dateFromString compare:dateFromString1] == NSOrderedAscending)
    {
        NSLog(@"1 is earlier than 2");

    } else
    {
        NSLog(@"dates are the same");

    }
于 2013-06-05T07:11:10.810 回答
1

问题出在日期格式化程序上。使用 ofmm代替MM分钟而ss不是SS秒。

[dateFormatter1 setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
于 2013-06-05T07:11:19.007 回答