iOS

Question

我知道如何获取两个 NSDate 之间的差异，如下所示

NSTimeInterval timeInterval = [[NSDate date] timeIntervalSinceDate:anyPreviousDate];

而且我知道它会 return 我 NSTimeInterval 在积极的几秒钟内。我想知道的是，如果我的 anyPreviousDate 大于 [NSDate date]，即 anyPreviousDate 尚未通过，它将 return 是什么，它将在未来出现。

只是好奇之前是否有人这样做过。

提前致谢。

Answer 1

如果 anyPreviousDate 实际上是十秒后，那么您的代码将 return -10.0。您经常会定义未来某个时间的 NSDates（例如从现在开始一分钟后做某事），所以这一点也不罕见。

Answer 2

我发现了另一种非常好的方法来做同样的事情...... 这是代码，我想与 Whosebug 分享。 Cocoa has couple of methods for this:

在 NSDate

– isEqualToDate:  
– earlierDate:  
– laterDate:  
– compare:

当你使用 - (NSComparisonResult)compare:(NSDate *)anotherDate 时，你会得到其中之一：

The receiver and anotherDate are exactly equal to each other, NSOrderedSame
The receiver is later in time than anotherDate, NSOrderedDescending
The receiver is earlier in time than anotherDate, NSOrderedAscending.

示例：

NSDate * now = [NSDate date];
NSDate * mile = [[NSDate alloc] initWithString:@"2001-03-24 10:45:32 +0600"];
NSComparisonResult result = [now compare:mile];

NSLog(@"%@", now);
NSLog(@"%@", mile);

switch (result)
{
    case NSOrderedAscending: NSLog(@"%@ is in future from %@", mile, now); break;
    case NSOrderedDescending: NSLog(@"%@ is in past from %@", mile, now); break;
    case NSOrderedSame: NSLog(@"%@ is the same as %@", mile, now); break;
    default: NSLog(@"erorr dates %@, %@", mile, now); break;
}

[mile release];

Answer 3

   if([previousDate compare:[NSDate date]] == NSOrderedDescending){
    // Previous date is greater than current date.i.e. previous date 
    //is still to come 
   }else{
   //Previous date is smaller then current date.i.e. previous date
   //has passed.
   }

NSDate 对象的比较方法returns NSComparisonResult，它是一个枚举。

NSComparisonResult 具有以下值。

如果左右操作数相等则返回NSOrderedSame

如果左操作数小于右操作数，则返回NSOrderedAscending

如果 ft 操作数大于右操作数，则返回 NSOrderedDescending

Answer 4

this's a screenshot to see

         NSDate * savedDate = [recordsDic[record.transactionId] modifiedDate];
         NSDate * newDate = record.modifiedDate;
         NSComparisonResult comparisonResult = [newDate compare:savedDate];
         NSTimeInterval timeInterval = [newDate timeIntervalSinceDate:savedDate];
         NSLog(@"\nsavedDate: %@   \nnewDate  : %@  \n===> timeInterval: %f",savedDate,newDate,timeInterval);
         if (comparisonResult == NSOrderedSame) {
             NSLog(@"they are same!!!!");
         } else {
             NSLog(@"they are NOT same!!!!");
         }

Console log:
2019-04-11 17:26:47.903059+0800 xxxxx[19268:24419134] 
savedDate: Thu Apr 11 15:47:23 2019   
newDate  : Thu Apr 11 15:47:23 2019  
===> timeInterval: 0.000365
2019-04-11 17:26:47.903193+0800 xxxxx[19268:24419134] they are NOT same!!!!

你相信吗！？但这是真的，我花了将近一整天的时间来解决这个问题。因为这不会一直发生！！！所以我强烈推荐： 1. 不要使用实例方法“- (NSComparisonResult)compare:(NSDate *)other;”比较，你会看到一些真正有线的东西，你无法弄清楚。 2. timeIntervalSinceDate 更精确。

iOS - 将 NSDate 与另一个 NSDate 进行比较

iOS - Comparing NSDate with another NSDate

objective-c

nsdate

nstimeinterval