iOS11中右滑手势导致返回按钮消失

iOS11中右滑手势与使用leftBarButtonItems添加的返回按钮并存，当右滑时，返回按钮会消失。渲染的时候发现返回按钮那一块完全被移除了。目前只在iOS11系统上发现这种情况，如果有知情的同学可以评论回复。

我的解决办法，直接上代码：

    UIButton *leftBtn = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 44.0, 44.0)];
    leftBtn.backgroundColor = [UIColor clearColor];
    leftBtn.contentHorizontalAlignment = UIControlContentHorizontalAlignmentLeft;
    [leftBtn setImage:[UIImage imageNamed:@"icon_back"] forState:UIControlStateNormal];
    [leftBtn addTarget:self action:@selector(backBtnAction:) forControlEvents:UIControlEventTouchUpInside];
UIBarButtonItem *leftItem = [[UIBarButtonItem alloc] initWithCustomView:leftBtn];
 
 if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 11.0) {
            //如果是iOS 11以上版本
            if ([leftItem.customView isKindOfClass:[UIButton class]]) {
                UIButton *leftButton = (UIButton *)leftItem.customView;
                //图片向左偏移5个像素
                leftButton.imageEdgeInsets = UIEdgeInsetsMake(0, -5.0, 0, 0);
            }
             self.navigationItem.leftBarButtonItem = leftItem;
        }else{
            UIBarButtonItem *negativeSpacer = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];
            negativeSpacer.tintColor = [UIColor redColor];
                    negativeSpacer.width = -5.0;  //偏移距离  -向左偏移, +向右偏移
            self.navigationItem.leftBarButtonItems = @[negativeSpacer,leftItem];
        }