您的UIImageView的高度与屏幕大小相同，如果您的视图大于屏幕大小，则白色视图将保留在底部。

let backgroundImage = UIImageView(frame: UIScreen.main.bounds)

使用滚动视图更新backgroundImage的帧，如下所示：

let backgroundImage = UIImageView(frame: self.my_view_2.bounds)
backgroundImage.autoresizingMask = [.flexibleHeight, .flexibleWidth] // In case if your my_view_2 frames increases
self.my_view_2.insertSubview(backgroundImage, at: 0)

把这段代码加到你的viewDidLoad（）中.可能会帮助你解决.

if #available(iOS 11.0, *) {
   scrollView.contentInsetAdjustmentBehavior = .never
} else {
   automaticallyAdjustsScrollViewInsets = false
}

试试这个

let backgroundImage = UIImageView(frame: my_view_2.bounds)
backgroundImage.clipsToBounds = true
backgroundImage.image = UIImage(named: "background_image")
backgroundImage.contentMode = .scaleToFill
self.my_view_2.addSubview(backgroundImage)

希望能有所帮助

self.my_view_2.layer.contents = #imageLiteral(resourceName: "background_image");