好的 - 一种方法...
从 iOS 11 开始（我假设您不需要更早的定位）， a 的子视图UIScrollView可以限制为滚动视图的Frame Layout Guide. 这使得将非滚动 UI 元素添加到滚动视图层次结构变得很容易。
基于此层次结构：
- view
- scrollView
- contentView
- element1
- element2
- element3
- UILayoutGuide
- footerView
我们要做的是：
- 将所有“可滚动”元素添加到 contentView
- 加上
UILayoutGuide将作为或“底部”可滚动元素的 contentView添加
- 最后将 footerView 添加到 scrollView，使其位于 z-order 的顶部
- 将footerView 约束到scrollView，
Frame Layout Guide使其保持原样
- 约束我们的heightAnchor
UILayoutGuide等于footerView的heightAnchor
因为 aUILayoutGuide是一个非渲染视图，所以它是不可见的，但它会创建从我们最后一个可视元素底部到 contentView 底部的空间——如果/当 footerView 改变高度时，它会自动改变高度。
这是一个完整的例子——scrollView / contentView / 3 imageViews / layout guide / translucent footerView：
class ExampleViewController: UIViewController {
let scrollView: UIScrollView = {
let v = UIScrollView()
v.backgroundColor = .lightGray
return v
}()
let contentView: UIView = {
let v = UIView()
v.backgroundColor = .cyan
return v
}()
let footerView: UILabel = {
let v = UILabel()
v.textAlignment = .center
v.textColor = .white
v.font = UIFont.systemFont(ofSize: 24.0, weight: .bold)
v.text = "Footer View"
v.backgroundColor = UIColor.black.withAlphaComponent(0.65)
return v
}()
var imgView1: UIImageView = {
let v = UIImageView()
v.backgroundColor = .red
v.image = UIImage(systemName: "1.circle")
v.tintColor = .white
return v
}()
var imgView2: UIImageView = {
let v = UIImageView()
v.backgroundColor = .green
v.image = UIImage(systemName: "2.circle")
v.tintColor = .white
return v
}()
var imgView3: UIImageView = {
let v = UIImageView()
v.backgroundColor = .blue
v.image = UIImage(systemName: "3.circle")
v.tintColor = .white
return v
}()
override func viewDidLoad() {
super.viewDidLoad()
// add 3 image views as the content we want to see
contentView.addSubview(imgView1)
contentView.addSubview(imgView2)
contentView.addSubview(imgView3)
// add contentView to srollView
scrollView.addSubview(contentView)
// add footer view to scrollView last so it's at the top of the z-order
scrollView.addSubview(footerView)
view.addSubview(scrollView)
[scrollView, contentView, footerView, imgView1, imgView2, imgView3].forEach {
$0.translatesAutoresizingMaskIntoConstraints = false
}
// "spacer" for bottom of scroll content
// we'll constrain it to the height of the footer view
let spacerGuide = UILayoutGuide()
contentView.addLayoutGuide(spacerGuide)
let g = view.safeAreaLayoutGuide
let svCLG = scrollView.contentLayoutGuide
let scFLG = scrollView.frameLayoutGuide
NSLayoutConstraint.activate([
// constrain scrollView view 40-pts on all 4 sides to view (safe-area)
scrollView.topAnchor.constraint(equalTo: g.topAnchor, constant: 40.0),
scrollView.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 40.0),
scrollView.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -40.0),
scrollView.bottomAnchor.constraint(equalTo: g.bottomAnchor, constant: -40.0),
// contentView view 0-pts top / leading / trailing / bottom to scrollView contentLayoutGuide
contentView.topAnchor.constraint(equalTo: svCLG.topAnchor, constant: 0.0),
contentView.leadingAnchor.constraint(equalTo: svCLG.leadingAnchor, constant: 0.0),
contentView.trailingAnchor.constraint(equalTo: svCLG.trailingAnchor, constant: 0.0),
contentView.bottomAnchor.constraint(equalTo: svCLG.bottomAnchor, constant: 0.0),
// contentView width == scrollView frameLayoutGuide width
contentView.widthAnchor.constraint(equalTo: scFLG.widthAnchor, constant: 0.0),
// imgView1 to top of contentView
imgView1.topAnchor.constraint(equalTo: contentView.topAnchor, constant: 0.0),
// imgView1 width / height
imgView1.widthAnchor.constraint(equalToConstant: 240.0),
imgView1.heightAnchor.constraint(equalToConstant: 240.0),
// imgView1 centerX to contentView centerX
imgView1.centerXAnchor.constraint(equalTo: contentView.centerXAnchor),
// imgView2 top to bottom of imgView1 + 20-pt spacing
imgView2.topAnchor.constraint(equalTo: imgView1.bottomAnchor, constant: 20.0),
// imgView2 width / height
imgView2.widthAnchor.constraint(equalToConstant: 200.0),
imgView2.heightAnchor.constraint(equalToConstant: 280.0),
// imgView2 centerX to contentView centerX
imgView2.centerXAnchor.constraint(equalTo: contentView.centerXAnchor),
// imgView3 top to bottom of imgView2 + 20-pt spacing
imgView3.topAnchor.constraint(equalTo: imgView2.bottomAnchor, constant: 20.0),
// imgView3 width / height
imgView3.widthAnchor.constraint(equalToConstant: 280.0),
imgView3.heightAnchor.constraint(equalToConstant: 320.0),
// imgView3 centerX to contentView centerX
imgView3.centerXAnchor.constraint(equalTo: contentView.centerXAnchor),
// spacerGuide top to bottom of actual content
// spacerGuide top to imgView3 bottom
spacerGuide.topAnchor.constraint(equalTo: imgView3.bottomAnchor, constant: 0.0),
// spacerGuide to leading / trailing / bottom of contentView
spacerGuide.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 0.0),
spacerGuide.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: 0.0),
spacerGuide.bottomAnchor.constraint(equalTo: contentView.bottomAnchor, constant: 0.0),
// footerView to leading / trailing / bottom of scrollView frameLayoutGuide
// (constrained to frameLayoutGuide so it won't scroll)
footerView.leadingAnchor.constraint(equalTo: scFLG.leadingAnchor, constant: 0.0),
footerView.trailingAnchor.constraint(equalTo: scFLG.trailingAnchor, constant: 0.0),
footerView.bottomAnchor.constraint(equalTo: scFLG.bottomAnchor, constant: 0.0),
// footerView height == scrollView height with 0.25 multiplier
// (so it will change height when scrollView changes height, such as device rotation)
footerView.heightAnchor.constraint(equalTo: scFLG.heightAnchor, multiplier: 0.25),
// finally, spacerGuide height equal to footerView height
spacerGuide.heightAnchor.constraint(equalTo: footerView.heightAnchor),
])
}
}
结果：
滚动到底部：
并旋转（所以我们看到 footerView 高度变化）一直滚动到底部：
编辑
具体问题的答案是：你不能。
滚动视图contentInset不是可以添加约束的对象......它是滚动视图的属性。就像您不能将滚动视图约束.backgroundColor到自动布局约束一样。