On 22 Sep 2016, at 02:02, Doug Hill <cocoa...@breaqz.com> wrote: >>> My question is: how can the compiler know that '==' in this case is a >>> NSString comparison? >>> Or is some other magic going on here? if so, which? >>> Does the compiler know it should perform some kind of dynamic method >>> dispatch? >> >> My guess, without seeing the code that set up the observer, is that it was >> also set up with @"mediaLibraryLoaded", and the compiler collects and reuses >> string constants, so the address is the same. I'd guess that if you ensure >> that the string is a unique variable, it won't work. >> >> NSString* s = [NSString stringWithFormat:@"%@%@%@", @"media", @"Library", >> @"Loaded"]; >> if(context == (__bridge void*)s) >> >> Steve via iPad > > For the above test, you could also try turning off the LLVM code-gen setting > "gcc_reuse_strings". > (Which parenthetically, you probably wouldn't want to do in shipping code, > particularly if you have a lot of strings.) > > But yeah, as everyone says, it's generally not a good thing to rely upon this > behavior, and just use -[NSString isEqual:]
Do *not* call methods on the context to a KVO observation! It is not guaranteed to actually be an object! It is not storage for user data, it is simply a unique identifier for your subscription to these KVO callbacks. -- Uli _______________________________________________ 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
