检查指定日期是今天、昨天还是将来的日期

Question

我有一个关于 NSDate 的疑问。我有一个日期，即“2011-10-04 07:36:38 +0000”，我想检查这个日期是昨天、今天还是未来的日期。

我该怎么办呢？

Answer 1

试试这个：

注意：根据您的需要更改日期格式。

NSDateFormatter* df = [[NSDateFormatter alloc] init];
[df setDateFormat:@"MM/dd/yyyy"];
NSDate* enteredDate = [df dateFromString:@"10/04/2011"];
NSDate * today = [NSDate date];
NSComparisonResult result = [today compare:enteredDate];
switch (result)
{
    case NSOrderedAscending: 
        NSLog(@"Future Date");
                    break;
    case NSOrderedDescending: 
        NSLog(@"Earlier Date");
                    break;
    case NSOrderedSame: 
        NSLog(@"Today/Null Date Passed"); //Not sure why This is case when null/wrong date is passed
                    break;
}

Answer 2

请参阅 Apple 关于日期计算的文档：

NSDate *startDate = ...;
NSDate *endDate = ...;

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

NSUInteger unitFlags = NSMonthCalendarUnit | NSDayCalendarUnit;

NSDateComponents *components = [gregorian components:unitFlags
                                          fromDate:startDate
                                          toDate:endDate options:0];
NSInteger months = [components month];
NSInteger days = [components day];

如果 days 介于 +1 和-1 那么你的约会对象就是“今天”的候选者。显然，您需要考虑如何处理时间。想必最简单的方法是将所有日期设置为相关日期的 00:00.00 小时（截断使用这样的方法计算日期），然后使用这些值进行计算。这样你今天会得到 0，昨天会得到 -1，明天会得到 +1，任何其他值同样会告诉你事情在未来或过去有多远。

Answer 3

根据您的需要使用以下任何内容，

– earlierDate:
– laterDate:
– compare:

请参阅此 http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSDate_Class/Reference/Reference.html

Answer 4

-(NSString*)timeAgoFor:(NSString*)tipping_date
{
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"yyyy-MM-dd"];
    NSDate *date = [dateFormatter dateFromString:tipping_date];
    NSString *key = @"";
    NSTimeInterval ti = [date timeIntervalSinceDate:[NSDate date]];
    key = (ti > 0) ? @"Left" : @"Ago";

    ti = ABS(ti);
    NSDate * today = [NSDate date];
    NSComparisonResult result = [today compare:date];

    if (result == NSOrderedSame) {
        return[NSString stringWithFormat:@"Today"];
    }
    else if (ti < 86400 * 2) {
        return[NSString stringWithFormat:@"1 Day %@",key];
    }else if (ti < 86400 * 7) {
        int diff = round(ti / 60 / 60 / 24);
        return[NSString stringWithFormat:@"%d Days %@", diff,key];
    }else {
        int diff = round(ti / (86400 * 7));
        return[NSString stringWithFormat:@"%d Wks %@", diff,key];
    }
}