> On May 20, 2015, at 1:04 PM, Alex Zavatone <z...@mac.com> wrote: > > Many times in the classes, an ivar is defined in the @interface of the class. > Sometimes not.
In the old days, before about 2006, the ivars had to be defined in the @interface. Nowadays it’s best to put them in the @implementation since they’re private to the implementation anyway. I always move them when updating old code. > Now, I remember back in 2012 that I could access a property within an > instance of the object without using self, but never knew if I was accessing > the ivar or the property itself simply by looking at the object. It’s simple, really: • “foo” is a variable — either an ivar or some sort of C variable (local, parameter, static, global.) • “self.foo” is a reference to a property. It’s equivalent to “[self foo]”, or if it’s on the left-hand-side of an assignment it’s “[self setFoo: …]”. There’s no ambiguity at all. A property name _has to_ go after a “.”, with an object value beforehand. An instance variable _cannot_ go after a “.” (It’s possible to refer to an ivar as “self->foo” but that syntax is old-fashioned and discouraged AFAIK.) Ivars and properties have entirely different namespaces, so even if a property has a backing ivar (i.e. is synthesized) the names don’t have to relate to each other. If you don’t explicitly use @synthesize, then I believe the ivar names created by the compiler will be the property name prefixed with “_”. I’m strongly against auto-synthesis; I think it was a bad idea to add it to Clang. It may save you from having to type “@synthesize”, but it leads to a lot of confusion, as shown here, by blurring the distinction between properties and ivars and creating ivars out of nowhere. And it can cause bugs if you meant a property to have explicit get or set methods but forgot to implement them (or worse, misspelled them!) I always turn it off in the target settings of my projects. —Jens _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) 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 arch...@mail-archive.com
