分页滚动视图上的中心元素

Question

I am creating UIImageViews programatically and scroll between them as pagination

How can I center each image with auto-layout programatically?

// manual attempt 
viewDidLoad() {

    self.scroll.frame = CGRect(x:0, y:0, width:self.view.frame.width, height:self.view.frame.height)

    let scrollWidth: CGFloat = self.scroll.frame.width

    let imgOne = UIImageView(frame: CGRect(x:65, y:120, width:180, height:300))
    let imgTwo = UIImageView(frame: CGRect(x:scrollWidth + 65, y:120, width:180, height:300))
    let imgThree = UIImageView(frame: CGRect(x:scrollWidth*2 + 65, y:120,width:180, height:300))

    imgOne.image = UIImage(named: "one.png")
    imgTwo.image = UIImage(named: "two.png")
    imgThree.image = UIImage(named: "three.png")

    imgOne.center = self.view.center // works
    imgTwo.center = ?? 
    imgThree.center = ??

    self.scroll.addSubview(imgOne)
    self.scroll.addSubview(imgTwo)
    self.scroll.addSubview(imgThree)

}

Answer 1

Use UICollectionView . You can set pagingEnabled for paging between images and UICollectionViewScrollDirectionHorizontal in layout for horizontal direction. See good example of using it here .