NSDate作为NSDictionary的键 [英] NSDate as keys for NSDictionary

问题描述

是否可以添加NSDate作为键和一些数组作为其值在NSDictionary中？

Is it possible to add NSDate as keys and some arrays as it values in a NSDictionary?

我没有任何要求将字典写入磁盘 - 归档或unarchive，就像这个家伙需要它： NSDictionary与NSDates作为键

I dont have any requirement of writing the dictionary to disk - archiving or unarchiving, just as this guy needs it: NSDictionary with NSDates as keys

但是，为什么我要NSDate被添加为键，具体是这样，我可以从字典中获取所有的键，并做一些计算，从一个范围内获取日期。

But, why I want NSDate to be added as keys specifically is so that I can fetch all keys from the dictionary and do some computations like, fetching the dates from within a range.

是否两个具有相同日期值的对象在创建时共享相同的内存？

Whether two objects with same date value share same memory when created?

是否可以使用NSDate作为键？

Is it possible to have NSDate as key? Also, what other problems I might face with this assumption?

感谢，

Raj

编辑：
发布我的问题后，我只是写了一个示例代码：

After posting my question, I just wrote a sample code:

NSDateComponents *dateComps = [[NSDateComponents alloc] init];
[dateComps setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
[dateComps setDay:1];
[dateComps setMonth:1];
[dateComps setYear:2012];
NSDate *date1 = [[NSCalendar currentCalendar] dateFromComponents:dateComps];
NSDate *date2 = [[NSCalendar currentCalendar] dateFromComponents:dateComps];
NSLog(@"Date 1 = %x, Date 2 = %x", date1, date2);

输出：

Date 1 = 7945610, Date 2 = bd03610

但是NSDictionary解释这两个NSDate对象是不同的？

But does the key comparison of NSDictionary interpret these 2 NSDate objects as different?

另一个编辑：

如果我应该使用NSDateFormatter转换NSDate到NSString，我不能直接检查范围内的日期。我将必须执行以下步骤：

Also, if I should convert NSDate to NSString using NSDateFormatter, I cannot directly check for dates within range. I will have to perform the following steps:

1. 从字典获取所有NSString数组键


2. 将它们转换回NSDate数组


3. 在范围内执行谓词和获取日期


4. 再次将这些日期转换为字符串数组


5. 现在使用这个字符串键从字典中获取值！

1. Get all NSString array of keys from dictionary
2. Convert them back to array of NSDate
3. Perform predicates and fetch dates within range
4. Again convert back those dates to an array of Strings
5. Now use this string keys to get values from dictionary!

/ p>

So, is there any better way?

推荐答案

是， NSDate 对象可以用作 NSDictionary - 任何对象类型都可以用作键，只要它支持 NSCopying 协议。使用 isEqual：和不通过指针值比较键。有关更多详细信息，请参阅 NSDictionary 文档中的概述部分。

Yes, NSDate objects can be used as keys for NSDictionary - any object type can be used as a key provided it supports the NSCopying protocol. Keys are compared using isEqual: and not by pointer value. See the Overview section of the NSDictionary documentation for more details.

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