iOS 怎麼設置 UITabBarController 的第n個item為第一響應者?

UITabBarController 裡面有個屬性：selectedIndex

@property(nonatomic) NSUInteger selectedIndex;

UITabBarController *VC = [[UITabBarController alloc]init];

VC.selectedIndex = n-1;

[self.navigationController pushViewController:VC animated:YES];