现在大多数App都有这种效果，实现原理大同小异。都是监听UITableView scrollViewDidScroll 方法去动态改变header frame。

QQ20180505-212023-HD.gif

1.懒加载定义UITableView

    lazy var tableview:UITableView = {
       var mytable = UITableView.init(frame: CGRect.init(x: 0, y: 0, width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height), style: .grouped)
        mytable.register(UITableViewCell.self, forCellReuseIdentifier: "cell")
        mytable.delegate = self
        mytable.dataSource = self
        return mytable
    }()

2.定义Header 背景图片

    lazy var headerView:UIImageView = {
        var header:UIImageView = UIImageView.init(frame: CGRect.init(x: 0, y: 0, width: UIScreen.main.bounds.width, height: 300))
        header.image = UIImage.init(named: "headbg")
        header.contentMode = .scaleAspectFill
        header.backgroundColor = UIColor.red
        return header
    }()

3. 给 tableHeaderView创建view视图

    override func viewDidLoad() {
        super.viewDidLoad()
        //自定义view 头像/登录/注册 按钮都可以放在上面
        let back:UIView = UIView.init(frame: CGRect.init(x: 0, y: 0, width: UIScreen.main.bounds.width, height: 300))
        back.backgroundColor = UIColor.green
        back.addSubview(headerView)
        self.tableview.tableHeaderView = back
        self.view.addSubview(self.tableview)
        // Do any additional setup after loading the view.
    }

4.创建监听scrollViewDidScroll

    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        //照片宽度
        let width = self.view.frame.size.width
        //偏移量y
        let yoffset = scrollView.contentOffset.y
        if yoffset<0 {
            let totalOffset = 300 + abs(yoffset)
            let f = totalOffset/300 //计算缩放比例
            self.headerView.frame = CGRect.init(x: -(width*f-width), y: yoffset, width: width*f, height: totalOffset)
        }
    }

上例是UIViewController 没有 UINavigationBar 的情况。如果有UINavigationBar 可将navigationbar 设置成透明 然后 适当设置 uitableview contentOffset,让uitableview 在 navigationbar下面。

override func viewWillAppear(_ animated: Bool) {
        //1.判断登录状态，load data
        //2.设置透明
        self.navigationController?.navigationBar.isTranslucent = true
  self.navigationController?.navigationBar.setBackgroundImage(UIImage.init(), for: .default)
        self.navigationController?.navigationBar.shadowImage = UIImage.init()
        self.navigationController?.navigationBar.barStyle = .blackTranslucent
    }

取消透明

    override func viewWillDisappear(_ animated: Bool) {
        self.navigationController?.navigationBar.setBackgroundImage(nil, for: .default)
        self.navigationController?.navigationBar.shadowImage = nil
        self.navigationController?.navigationBar.barStyle = .default
        self.navigationController?.navigationBar.isTranslucent = false
    }