iOS 解决右按钮偏移量

   if([[UIDevice currentDevice].systemVersion floatValue] >= 11.0){

        if(kScreenWidth>375){

            space =20.f;

        }

    }else if(!kiOS11Later){

        space =0;

    }

    UIView *aVie = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 56-space, 40.0)];

    aVie.clipsToBounds = NO;

    [aVieaddSubview:_rightItem];

    UIBarButtonItem *barButtonItem = [[UIBarButtonItem alloc]initWithCustomView:aVie];

    if(@available(iOS11.0, *)) {

        self.navigationItem.rightBarButtonItems = @[barButtonItem];

    }else{

        UIBarButtonItem * fixSpaceItem = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];

        fixSpaceItem.width= -16.f;

        self.navigationItem.rightBarButtonItems=@[fixSpaceItem,barButtonItem];

    }