NSApplication+SystemVersion.m

@implementation NSApplication (SystemVersion)

- (void)getSystemVersionMajor:(unsigned *)major
                        minor:(unsigned *)minor
                       bugFix:(unsigned *)bugFix;
{
    OSErr err;
    SInt32 systemVersion, versionMajor, versionMinor, versionBugFix;
    if ((err = Gestalt(gestaltSystemVersion, &systemVersion)) != noErr) goto fail;
    if (systemVersion < 0x1040)
    {
        if (major) *major = ((systemVersion & 0xF000) >> 12) * 10 +
            ((systemVersion & 0x0F00) >> 8);
        if (minor) *minor = (systemVersion & 0x00F0) >> 4;
        if (bugFix) *bugFix = (systemVersion & 0x000F);
    }
    else
    {
        if ((err = Gestalt(gestaltSystemVersionMajor, &versionMajor)) != noErr) goto fail;
        if ((err = Gestalt(gestaltSystemVersionMinor, &versionMinor)) != noErr) goto fail;
        if ((err = Gestalt(gestaltSystemVersionBugFix, &versionBugFix)) != noErr) goto fail;
        if (major) *major = versionMajor;
        if (minor) *minor = versionMinor;
        if (bugFix) *bugFix = versionBugFix;
    }
    
    return;
    
fail:
    NSLog(@"Unable to obtain system version: %ld", (long)err);
    if (major) *major = 10;
    if (minor) *minor = 0;
    if (bugFix) *bugFix = 0;
}

@end

/*
int main(void)
{
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
	
    unsigned major, minor, bugFix;
    [[NSApplication sharedApplication]
	 getSystemVersionMajor:&major minor:&minor bugFix:&bugFix];
    NSLog(@"%u.%u.%u", major, minor, bugFix);
    
    [pool release];
    return EXIT_SUCCESS;
}

*/