Re: Using CFHash to tell if a CFTypeRef has changed?
Re: Using CFHash to tell if a CFTypeRef has changed?
- Subject: Re: Using CFHash to tell if a CFTypeRef has changed?
- From: Jens Alfke <email@hidden>
- Date: Mon, 11 Jan 2016 09:57:51 -0800
> On Jan 11, 2016, at 9:48 AM, Dave <email@hidden> wrote:
>
> I have an object that is a wrapper around a CFTypeRef. I’d like to be able to check if this object has changed, can I use the safely use the CFHash() function to do this.
No. If the object has changed, its hash isn’t guaranteed to change; there exist hash collisions where two different values have the same hash. (This is inevitable since there are only 2^32 hash values, but a nearly infinite number of different strings, arrays, etc.)
—Jens
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