Swift: ScrollView上拉滑动到下一页

前言:看看上次发布文章已经是三年之前了. 这三年生活和工作经历都是起起伏伏.幸运的是,对学会未知的东西,还是觉得很快乐.iOS这条路能走多久不知道.只是做好当下,把每天遇到的新tips整理一下吧.

需求: 滑动上一页,到底部时候,上拉滑动到下一页.

实现思路: 底部ScrollView,上面的内容也用ScrollView

要点1. 底部ScrollView.isPagingEnabled = true
要点2. scrollview准确设置contentSize

class ViewController: UIViewController {
    
    var mainScrollView = UIScrollView()
    
    var topScrollView = UIScrollView()
    
    var bottomScrollView = UIScrollView()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        mainScrollView.frame = CGRect(x: 0, y: 0, width: view.bounds.width, height:  view.bounds.height)
        mainScrollView.contentSize = CGSize(width: 0, height: mainScrollView.frame.size.height * 2)
        mainScrollView.isPagingEnabled = true
        mainScrollView.delegate = self
        view.addSubview(mainScrollView)
        
        let scrollViewHeight = mainScrollView.frame.size.height
        
        topScrollView.frame = CGRect(x: 0, y: 0, width: mainScrollView.frame.size.width, height: scrollViewHeight)
        topScrollView.backgroundColor = .green
        topScrollView.contentSize = CGSize(width: 0, height: scrollViewHeight * 1.5)
        topScrollView.showsVerticalScrollIndicator = false
        topScrollView.delegate = self
        mainScrollView.addSubview(topScrollView)
        
        bottomScrollView.frame = CGRect(x: 0, y: topScrollView.frame.size.height, width: mainScrollView.frame.size.width, height: mainScrollView.frame.size.height)
        bottomScrollView.contentSize = CGSize(width: 0, height: scrollViewHeight)
        bottomScrollView.backgroundColor = .orange
        mainScrollView.addSubview(bottomScrollView)
        
    }
}