> On Apr 22, 2016, at 5:05 PM, Greg Parker <[email protected]> wrote:
> 
>> On Apr 22, 2016, at 2:36 PM, Charles Srstka via swift-evolution 
>> <[email protected] <mailto:[email protected]>> wrote:
>> 
>> One comment:
>> 
>> "In the most common case where a developer does not provide a custom 
>> reference type, then the backing store is our existing NSData and 
>> NSMutableData implementations. This consolidates logic into one place and 
>> provides cheap bridging in many cases (see Bridging for more information).”
>> 
>> Would it not be more efficient to bridge to the C-based CFData and 
>> CFMutableData implementations instead, to avoid the object overhead?
> 
> Not necessarily. Foundation often has less overhead than CF nowadays.

That’s interesting; I hadn’t known that. What causes that? My understanding had 
always been that the NS and CF objects, being toll-free bridged to each other, 
shared the same default implementations, with the only difference being that 
the NS versions involved the overhead from objc_msgSend() as well as, in many 
cases, an autorelease.

Charles

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