iOS :navigationbar隐藏之後手動加側滑傳回

//顯示navigationbar
- (void)viewWillAppear:(BOOL)animated{ 
        [self.navigationController setNavigationBarHidden: YES];

//隐藏navigationbar
-(void)viewWillDisappear:(BOOL)animated{
        [self.navigationController setNavigationBarHidden: NO];

//側滑傳回手勢
 UIScreenEdgePanGestureRecognizer *gesture = [[UIScreenEdgePanGestureRecognizer alloc] initWithTarget:self action:@selector(clickBackBtn)];

 gesture.edges = UIRectEdgeLeft;

[self.view addGestureRecognizer:ges];