NSScreenMainScreenSpikeAppDelegate.m

@implementation NSScreenMainScreenSpikeAppDelegate

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
    [NSTimer scheduledTimerWithTimeInterval:1.0
                                     target:self
                                   selector:@selector(pollScreen:)
                                   userInfo:nil
                                    repeats:YES];
}

- (void)pollScreen:(NSTimer*)timer_ {
    NSLog(@"%@", [[[NSScreen mainScreen] deviceDescription] description]);
}

@end