水平ScrollView以编程方式弹回问题

Question

我有一个简单的ScrollView，里面有4个buttons，我想把它做成一个horizontal ScrollView。

这是我的设置方式：

let itemScrollView: UIScrollView = {
    let v = UIScrollView()
    v.translatesAutoresizingMaskIntoConstraints = false
    v.backgroundColor = .red
    return v
}()

我这样限制它及其内容：

itemView.addSubview(itemScrollView)
itemScrollView.addSubview(imageButton)
itemScrollView.addSubview(priceButton)
itemScrollView.addSubview(linkButton)
itemScrollView.addSubview(noteButton)
self.addSubview(dropDownButton)

itemView.heightAnchor.constraint(equalToConstant: 60).isActive = true

dropDownButton.heightAnchor.constraint(equalToConstant: 35).isActive = true
dropDownButton.widthAnchor.constraint(equalToConstant: 150).isActive = true
dropDownButton.trailingAnchor.constraint(equalTo: itemView.trailingAnchor, constant: -20).isActive = true
dropDownButton.centerYAnchor.constraint(equalTo: itemView.centerYAnchor).isActive = true

itemScrollView.topAnchor.constraint(equalTo: itemView.topAnchor).isActive = true
itemScrollView.leadingAnchor.constraint(equalTo: itemView.leadingAnchor).isActive = true
itemScrollView.trailingAnchor.constraint(equalTo: dropDownButton.leadingAnchor).isActive = true
itemScrollView.bottomAnchor.constraint(equalTo: itemView.bottomAnchor).isActive = true

imageButton.heightAnchor.constraint(equalToConstant: 25).isActive = true
imageButton.widthAnchor.constraint(equalToConstant: 25).isActive = true
imageButton.centerYAnchor.constraint(equalTo: itemScrollView.centerYAnchor).isActive = true
imageButton.leadingAnchor.constraint(equalTo: itemScrollView.leadingAnchor, constant: 20).isActive = true

priceButton.heightAnchor.constraint(equalToConstant: 25).isActive = true
priceButton.widthAnchor.constraint(equalToConstant: 25).isActive = true
priceButton.centerYAnchor.constraint(equalTo: itemScrollView.centerYAnchor).isActive = true
priceButton.leadingAnchor.constraint(equalTo: imageButton.leadingAnchor, constant: 45).isActive = true

linkButton.heightAnchor.constraint(equalToConstant: 25).isActive = true
linkButton.widthAnchor.constraint(equalToConstant: 25).isActive = true
linkButton.centerYAnchor.constraint(equalTo: itemScrollView.centerYAnchor).isActive = true
linkButton.leadingAnchor.constraint(equalTo: priceButton.leadingAnchor, constant: 45).isActive = true

noteButton.heightAnchor.constraint(equalToConstant: 25).isActive = true
noteButton.widthAnchor.constraint(equalToConstant: 25).isActive = true
noteButton.centerYAnchor.constraint(equalTo: itemScrollView.centerYAnchor).isActive = true
noteButton.leadingAnchor.constraint(equalTo: linkButton.leadingAnchor, constant: 45).isActive = true

最后，它看起来确实像我想要的样子（第四个按钮隐藏在dropDownButton后面），但是您只能滚动 vertical 。

更新：

通过添加以下代码行，我可以水平滚动：

v.alwaysBounceHorizontal = true

但是现在的问题是，滚动后它总是向左“弹回”。我该如何解决该问题？

Answer 1

您要使视图控制器符合UIScrollViewDelegate，设置scrollView.delegate = self并实现scrollViewDidScroll方法，如下所示：

func scrollViewDidScroll(scrollView: UIScrollView) {
    if scrollView.contentOffset.y != 0 {
        scrollView.contentOffset.y = 0
    }
}