Re: NSDictionary key types
Re: NSDictionary key types
- Subject: Re: NSDictionary key types
- From: Jon Sigman <email@hidden>
- Date: Thu, 6 Jan 2011 13:39:06 -0800 (PST)
On Jan 6, 2011, at 1:24 PM, David Duncan wrote:
> The short of it is that its a value that allows you to quickly tell if
>something is worth looking at more closely for equality. As a real world example
>a hash code is equivalent to saying "this object is short, this object is tall"
>without breaking out a ruler to determine if they are the same length.
-----
Okay, so the take-away from all this is that for the purpose of using objects as
keys, I can rely on two NSStrings hashes being equal if their string values are
equal; the same goes for two NSNumbers, etc. (though NSNumber might be a more
problematic case since it can be evaluated in numerous different ways, -int
-float, ...?).
If I've understood everything correctly, then the following two (contrived)
objects have the same hash value and will return TRUE from -isEqual:
id myStr1 = @"8760";
id myStr2 = [[NSNumber numberWithInt:8760]stringValue];
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