超简单方法实现iPhone通讯录标题动画

QQ20171208-164735-HD.gif

说一下思路: 红色就是tableview的tableHeaderView；橘色就是分区头，直接上代码

import UIKit

class BgViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
    var label = UILabel()
    var tableView = UITableView.init(frame: CGRect.zero, style: .plain)
    var navHeight: CGFloat = 0.0
    var namelabel = UILabel()

    override func viewDidLoad() {
        super.viewDidLoad()
        navHeight = (self.navigationController?.navigationBar.frame.maxY)!
        print(navHeight)
        self.tableView.frame = CGRect(x: 0, y: 0,width: self.view.frame.size.width,height:  self.view.frame.size.height)
        self.view.addSubview(self.tableView)
        self.tableView.delegate = self
        self.tableView.dataSource = self
        
        //注册UITableView，cellID为重复使用cell的Identifier
        self.tableView.register(UITableViewCell.self, forCellReuseIdentifier: "cellID")
        
        label.backgroundColor = UIColor.red
        label.frame = CGRect(x: 0, y: 0,width: self.view.frame.size.width,height: 50)
        label.text = "我是大标题"
        label.font = UIFont.boldSystemFont(ofSize: 21)
        label.textColor = UIColor.black
        self.tableView.tableHeaderView = label

        let titleview = UIView()
        titleview.frame = CGRect(x: 0, y: 0,width: self.view.frame.size.width * 0.6,height: 40)
        titleview.layer.masksToBounds = true
        self.navigationItem.titleView = titleview

        self.namelabel.frame = CGRect(x: 0, y: 40,width: self.view.frame.size.width * 0.6,height: 40)
        self.namelabel.textColor = UIColor.black
        self.namelabel.text = "我是大标题"
        self.namelabel.textAlignment = .center
        titleview.addSubview(self.namelabel)
        
    }

    func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return 20
    }
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = (tableView.dequeueReusableCell(withIdentifier: "cellID", for: indexPath)) as UITableViewCell
        cell.textLabel?.text = "我是第\(indexPath.row)行"
        return cell
    }
    func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
        return 40
    }
    
    func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
        let viw = UIView()
        viw.frame = CGRect(x: 0, y: 0,width: self.view.frame.size.width,height: 40)
        viw.backgroundColor = UIColor.orange
        let ser = UISearchBar()
        for sub in ser.subviews {
            sub.subviews.first?.removeFromSuperview()
        }
        ser.placeholder = "搜索"
        ser.frame = CGRect(x: 0, y: 0,width: 300,height: 40)
        ser.center = viw.center
        viw.addSubview(ser)
        return viw
    }
    func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
        return 40
    }

    
    func scrollViewDidScroll(_ scrollView: UIScrollView) {

        //上滑时，tableview的headview完全被navigationBar遮住显示标题
        if scrollView.contentOffset.y >  label.frame.size.height - navHeight {
            
        }else{
            self.namelabel.frame.origin.y = -scrollView.contentOffset.y - 24
            if self.namelabel.frame.origin.y <= 0 {
                self.namelabel.frame.origin.y = 0
            }
        }
        //下拉放大字体，这里的30是增大因子，不可以太小，不然字体会很大-----abs绝对值
        if scrollView.contentOffset.y < -navHeight {
            let font = abs(scrollView.contentOffset.y) / 30.0
            label.font = UIFont.boldSystemFont(ofSize: 21 + font)
        }
    }
}