UINavigationBar *navBar = [UINavigationBar appearance];
    // 返回按钮设置样式处理
    if (@available(iOS 11.0, *)){
        // 图片
        UIImage *backButtonImage =  [[CKImageViewOfIconFont imageWithIcon:LGIcon_return
                                                                     size:20
                                                                    color:LGWhiteColor]
                                     imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
        navBar.backIndicatorImage = backButtonImage;
        navBar.backIndicatorTransitionMaskImage = backButtonImage;
    } else {
        // 图片
        UIImage *backButtonImage = [[CKImageViewOfIconFont imageWithIcon:LGIcon_return
                                                                    size:20
                                                                   color:LGWhiteColor]
                                    resizableImageWithCapInsets:UIEdgeInsetsMake(0, 30, 0, 0)];
        [item setBackButtonBackgroundImage:backButtonImage
                                  forState:UIControlStateNormal
                                barMetrics:UIBarMetricsDefault];
    }