以编程方式将图像位置放置在按钮顶部

Place image position on top of button programatically

我点击了一个按钮,我需要在按钮操作中显示图像视图,我喜欢下面的操作

    let imageName = "pointed_image.png"
    let image = UIImage(named: imageName)
    let imageView = UIImageView(image: image!)
    self.addSubview(imageView)

现在我想将该图像放置在按钮的顶部,使图像的底部中心正好位于按钮的顶部中心。 (想象一下标注视图如何在地图中显示,其中图钉是位置(在我的场景中是按钮),而标注警报是位置的 "starbucks callout"(在我的场景中是图像)-

请问我该如何修改下面的代码以满足要求

    //Build image view
    let imageName = "pointed_image.png"
    let image = UIImage(named: imageName)
    let imageView = UIImageView(image: image!)

    //Get Button frame
    let btnFrame = self.infoButton.frame

    //position image on top of buttom
    // CODE TO MODIFY BELOW
    var imgFrame: CGRect = imageView.frame
    imgFrame.origin.x = btnFrame.origin.x + 10
    imgFrame.origin.y = btnFrame.origin.y - 10
    imageView.frame = imgFrame
    self.addSubview(imageView)

我会使用 imageViewcenter 属性 来正确放置它:

                           // aligned by centers in x axis
imageView.center = CGPoint(x: self.infoButton.center.x, 
                           // in y axis, using buttons origin and imageView's height placed right on top of the button
                           y: self.infoButton.frame.origin.y - (imageView.bounds.height / 2))