> On 2016 Aug 27, at 23:09, Keary Suska <[email protected]> wrote: > >> >> On Aug 27, 2016, at 5:22 AM, Andreas Falkenhahn <[email protected]> >> wrote: >> >> Consider the following example properties: >> >> NSApplication: @property(strong) NSMenu *mainMenu >> NSFont: @property(readonly, copy) NSString *familyName >> NSColorPanel: @property(copy) NSColor *color >> >> AFAIU I must not release the NSMenu/NSString/NSColor obtained from these >> properties because I don't own the objects returned by those properties and >> Apple's memory management policy docs clearly say: >> >> "You must not relinquish ownership of an object you do not own" >> >> So I think I've got that right but I'd be glad if somebody could just >> confirm that I got it right ;) >> >> I'm just a little confused because of the keywords "strong" and "copy" in >> the @property declarations but AFAIU these only refer to setting those >> properties, not getting those properties, i.e. the object is copied when >> *setting* the property, not when *getting* it. Right? >> >> And another question: Can it also happen that a class has a property >> which returns an object which I *must* release or is it a general rule >> that getting a @property always returns objects which I do not own >> and hence mustn't released? > > There are only specific method conventions that establish ownership: > alloc+init and new. This is because ownership should only be granted when > specifically requested by the caller. There is no good reason for an object > to require that a caller own a returned object. Now, some API could decide to > buck the convention and have a different object construction naming, but the > point is the same. If an API does anything else, it is badly designed. Cocoa > will never do this. > > One could even argue (and some have) that there is no good reason for *any* > object method to return a retained object, as that forces the caller to > explicitly require ownership. And that is key: ownership is a function of the > caller, not the object. > > HTH, > > Keary Suska > Esoteritech, Inc. > "Demystifying technology for your home or business" > > Just to keep everyone on the rules, I'm going to post the docs links. It's too easy to quote it wrong. (not saying anybody did)
Objective-C https://developer.apple.com/library/mac/documentation/General/Conceptual/DevPedia-CocoaCore/MemoryManagement.html https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/MemoryMgmt/Articles/MemoryMgmt.html Core Foundation (because you WILL use it at some point) https://developer.apple.com/library/mac/documentation/CoreFoundation/Conceptual/CFMemoryMgmt/Concepts/Ownership.html _______________________________________________ Cocoa-dev mailing list ([email protected]) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [email protected]
