I'm trying to understand how Mac OS X actually implements the predefined objects like NSApplication. Not in detail by function, but where the code lives. This is by way of understanding what happens if the SDK version doesn't match the system version. Let's suppose I would like to use an imaginary method [NSApplication doCoolStuff] which was added in Mac OS 10.15, but I'm linking with the 10.14 SDK.
So, where does doCoolStuff actually exist? I can think of several possibilities. 1. The code for NSApplication and its methods is linked entirely into my application. This makes it self contained, though it might depend on system calls and external services. So NSApplication exists inside my application, and it runs the version written as part of the SDK I link with (10.14). There is no way for me to call [NSApplication doCoolStuff] , because it doesn't exist in the NSApplication I am using (10.14 runtime). 2. The code for NSApplication is dynamically linked from system-provided shared code of some kind, using the same code regardless of the SDK version used. The shared code may include some differences according to info it has on the SDK used to build the current app. In this case perhaps I could call [NSApplication doCoolStuff], though not by coding that; something involving NSSelectorFromString. 3. The code for NSApplication is dynamically linked from system-provided shared code of some kind, using code dependent on the SDK version used. The methods provided will depend on the SDK version used. This would imply that, like case 1, is no way for me to call [NSApplication doCoolStuff] , because it doesn't exist in the NSApplication runtime I am using. 4. The code for NSApplication is a stub to some other kind of external interface I never heard of... Thanks in advance! _______________________________________________ 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
