Have you read https://developer.apple.com/library/tvos/documentation/Swift/Conceptual/BuildingCocoaApps/InteractingWithCAPIs.html#//apple_ref/doc/uid/TP40014216-CH8-ID17 ?
Zhaoxin On Fri, Jul 29, 2016 at 4:55 PM, James Campbell via swift-users < swift-users@swift.org> wrote: > Do you know of any resources to brush up on the pointer aspect of swift ? > > > *___________________________________* > > *James⎥Head of Trolls* > > *ja...@supmenow.com <ja...@supmenow.com>⎥supmenow.com > <http://supmenow.com>* > > *Sup* > > *Runway East * > > *10 Finsbury Square* > > *London* > > * EC2A 1AF * > > On 29 July 2016 at 09:10, Dmitri Gribenko <griboz...@gmail.com> wrote: > >> On Fri, Jul 29, 2016 at 12:55 AM, James Campbell <ja...@supmenow.com> >> wrote: >> > So this: >> > >> > if let data = someArrayGeneratingFunction() { >> > cFunction(UnsafeMutablePointer(data)) >> > } >> > >> > Has issues with the array passed to c getting corrupted, but this >> doesn't: >> > >> > let data = someArrayGeneratingFunction() >> > >> > if let data = data { >> > cFunction(UnsafeMutablePointer(data)) >> > } >> >> Neither piece of code is guaranteed to work. (You are just getting >> lucky that the second one happens to work.) Array-to-pointer >> conversion only extends the lifetime of the array until the immediate >> function call returns. So after UnsafeMutablePointer(data) returns, >> the array can be freed. >> >> Use someArrayGeneratingFunction.withUnsafeMutableBuffer { ... } instead. >> >> Dmitri >> >> -- >> main(i,j){for(i=2;;i++){for(j=2;j<i;j++){if(!(i%j)){j=0;break;}}if >> (j){printf("%d\n",i);}}} /*Dmitri Gribenko <griboz...@gmail.com>*/ >> > > > _______________________________________________ > swift-users mailing list > swift-users@swift.org > https://lists.swift.org/mailman/listinfo/swift-users > >
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