在另一个ViewController中打开全尺寸图像，可以像Whatsapp那样进行缩放

import UIKit

class ImageViewController: UIViewController, UIScrollViewDelegate {
    var scrollView: UIScrollView!
    var imageView: UIImageView!
    
    var image: UIImage!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建UIScrollView
        scrollView = UIScrollView(frame: view.bounds)
        scrollView.delegate = self
        scrollView.minimumZoomScale = 1.0
        scrollView.maximumZoomScale = 3.0
        view.addSubview(scrollView)
        
        // 创建UIImageView
        imageView = UIImageView(image: image)
        imageView.contentMode = .scaleAspectFit
        scrollView.addSubview(imageView)
        
        // 添加缩放手势识别器
        let pinchGesture = UIPinchGestureRecognizer(target: self, action: #selector(handlePinch(_:)))
        scrollView.addGestureRecognizer(pinchGesture)
    }
    
    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        
        // 设置UIScrollView的contentSize为图像的原始尺寸
        scrollView.contentSize = image.size
        
        // 重置UIImageView的frame
        imageView.frame = CGRect(origin: .zero, size: image.size)
    }
    
    // UIScrollViewDelegate方法，返回要缩放的视图
    func viewForZooming(in scrollView: UIScrollView) -> UIView? {
        return imageView
    }
    
    @objc func handlePinch(_ gestureRecognizer: UIPinchGestureRecognizer) {
        // 根据手势的缩放比例更新UIScrollView的缩放比例
        scrollView.zoomScale *= gestureRecognizer.scale
        gestureRecognizer.scale = 1.0
    }
}