It’s not 100% complete, and I have quite a few changes to make to make it “feel” like a real Objective-C pro wrote it, but it works today.

P8Engine* p8 = [[P8Engine alloc] initWithOptions:kP8APIKey 
                                    appKey:kP8AppKey 
                                    delegate:tDelegate];
if (p8)
{
    // Validate user
    [p8 userValidate];

    // Get user sevices.
    [p8 userServices];

    // Get system services.
    [p8 systemServices];

    // Post something.
    [p8 userPostStatus:@"Hello ping.fm."];

    [p8 release];
}

Get the P8 Objective-C engine for ping.fm here.