import UIKit

class ViewController: UIViewController ,UIScrollViewDelegate{

    override func viewDidLoad() {

        super.viewDidLoad()

        let scrollView = UIScrollView.init()

        scrollView.frame = self.view.bounds

        let imageView = UIImageView.init(image: UIImage.init(named: "1"))

        scrollView.contentSize = imageView.bounds.size

        scrollView.addSubview(imageView)

        self.view.addSubview(scrollView)

        // 手势缩放大小

        // 要实现放大缩小功能, 需要指定 UIScrollView 的允许缩放的最大和最小比例 (默认都是 1.0)

        // 同时 delegate 属性指定一个委托类, 委托类要继承 UIScrollViewDelegate 协议, 并实现 viewForZooming 方法

        scrollView.minimumZoomScale = 0.1 //最小比例

        scrollView.maximumZoomScale = 3 //最大比例

        scrollView.delegate = self

    }

    func viewForZooming(in scrollView: UIScrollView) -> UIView? {

        for subview : AnyObject in scrollView.subviews {

            if subview.isKind(of: UIImageView.classForCoder()) {

                return subview as? UIView

            }

        }

        return nil

    }

    //视图滚动中一直触发

    func scrollViewDidScroll(_ scrollView: UIScrollView) {

        print("x:\(scrollView.contentOffset.x) y:\(scrollView.contentOffset.y)")

    }

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

        // Dispose of any resources that can be recreated.

    }

}

swift 实践- 14 -- UIScrollView