將返回按鈕的樣式改為自己的圖片，這樣能夠保留系統(tǒng)的返回手勢。

  UIImage *backImage = [UIImage imageNamed:@"backNor"];
  [[UIBarButtonItem appearance] setBackButtonBackgroundImage:[backImage resizableImageWithCapInsets:UIEdgeInsetsMake(0, backImage.size.width, 0, 0)]
                                                      forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
  [[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(-233, 0) forBarMetrics:UIBarMetricsDefault];