<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Nov 3, 2016, at 1:46 PM, Chris Bailey via swift-server-dev <<a href="mailto:swift-server-dev@swift.org" class="">swift-server-dev@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><tt style="font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><font size="2" class="">> Well, GCD is already an example which does not use NSData but DispatchData. So if everything else is based on NSData, a GCD client would need to map/copy the DispatchData into an NSData.</font></tt><span style="font-family: Helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class=""><span class="Apple-converted-space"> </span></span><br style="font-family: Helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br style="font-family: Helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><font size="2" face="sans-serif" style="font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">Which is something that Foundation itself has to do for URLSession - I think its a pretty direct mapping, but there would be wider benefits of solving that issue.<br class=""></font></div></blockquote></div><br class=""><div class="">In ObjC dispatch_data_t is effectively toll-free-bridged with NSData, but when people want a flattened representation and they invoke -bytes, a new mapping has to be created into which the contiguous bytes are copied.</div><div class=""><br class=""></div><div class="">For this reason, we recommend using -[NSData enumerateByteRangesUsingBlock:] from now on. Obviously sometimes you need a contiguous buffer, but at least we can defer the copying as much as possible if concatenating dispatch_data objects.</div><div class=""><br class=""></div><div class="">--sma</div><div class=""><br class=""></div></body></html>