if ([detailItem isEqualToString:@"Test"]) {
TestViewController *testViewController = [[TestViewController alloc] initWithNibName:@"TestView" bundle:nil];
//since self.viewControllers is immutable, let's make our own temporary copy.
NSMutableArray *tempArray = [self.viewControllers mutableCopy];
//switcheroo with the new view controller
[tempArray replaceObjectAtIndex:1 withObject:testViewController];
// our new view controller is retained by the array, so let's release it
[testViewController release];
//set the new array to be displayed
self.viewControllers = tempArray;
//clean up - out mutableCopy returns a retained object
[tempArray release];
}