Re: Gracefully failing on unsupported OS version

FROM : Ali Ozer
DATE : Mon Apr 18 20:13:37 2005

In addition to setting the LSMinimumSystemVersion key as others have 
described, you can do one of several things, such as check AppKit 
version number:

  if (floor(NSAppKitVersionNumber) <= NSAppKitVersionNumber10_3) {
    /* On a 10.3.x or earlier system, put up alert */
  }

or check for the Tiger class in question:

  if (!NSClassFromString(@"NStigeronlyclass")) {
    /* On a 10.3.x or earlier system, put up alert */
  }

If you use Tiger symbols or function calls (not methods or classes) 
which are not appropriately weakly linked (they aren't declared as 
AVAILABLE_MAC_OS_X_VERSION_10_4_AND_LATER), your app might refuse to 
launch at all.    From what you describe below this doesn't seem to 
be the problem though.

Ali






Begin forwarded message:

> From: John Brownlow <<email_removed>>
> Date: April 18, 2005 10:43:56 PDT
> To: Cocoa List <<email_removed>>
> Subject: Gracefully failing on unsupported OS version
>
>
> My app is targeted at 10.4 and better. I know that whatever I do, 
> people are going to download it and try to use it on earlier 
> versions. I don't want to use an installer, just the drag-to-
> Applications thing. However, as currently configured, on pre-10.4 
> systems the app just fails to launch without a word of explanation. 
> The syslog shows that the cause of the crash is "failed 
> objc_getClass(NS**tigerOnlyClass**)"
>
> What's the nicest way of catching this problem without using an 
> installer? If the app won't launch in, say, 10.3, how can I tell 
> the user very politely that they need to upgrade if they want to 
> use my app?
>
>
> --
> John Brownlow
> Deep Fried Films, Inc
>
> http://www.johnbrownlow.com
> http://www.pinkheadedbug.com
>