     }
     
     // MARK: - --------------------代理方法--------------------
-    // MARK: - 代理种类注释
-    // MARK: 代理函数注释
+    
+    // MARK: UINavigationControllerDelegate
+    func navigationController(navigationController: UINavigationController, didShowViewController viewController: UIViewController, animated: Bool) {
+        if (navigationController.respondsToSelector(Selector("interactivePopGestureRecognizer"))) {
+            navigationController.interactivePopGestureRecognizer?.enabled = true
+        }
+    }
     
     // MARK: - --------------------属性相关--------------------
     // MARK: 属性操作函数注释


import UIKit

class BBRootViewController: UIViewController {
    
    // MARK: - --------------------System--------------------
    

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    
    override func viewWillAppear(animated: Bool) {
        super.viewWillAppear(animated)
        
        self.navigationController?.delegate = self
    }
    
    override func viewWillDisappear(animated: Bool) {
        super.viewWillDisappear(animated)
        
        self.navigationController?.delegate = nil
    }
    
    // MARK: - --------------------功能函数--------------------
