swift 从导航堆栈中获取以前的视图控制器

Posted 2021-05-19

extension UINavigationController {
    
    func previousViewController() -> UIViewController?{
        
        let lenght = self.viewControllers.count
        
        let previousViewController: UIViewController? = lenght >= 2 ? self.viewControllers[lenght-2] : nil
        
        return previousViewController
    }
    
}