Swift - 图像控件（UIImageView）的用法

let imageView = UIImageView(image:UIImage(named:"image1"))
imageView.frame = CGRect(x:10, y:30, width:300, height:150)
self.view.addSubview(imageView)

2，改变图片

imageView.image = UIImage(named:"icon2")

3，从文件目录中获取图片

let path = Bundle.main.path(forResource: "ball", ofType: "png")
let newImage = UIImage(contentsOfFile: path!)
let imageView = UIImageView(image:newImage)
self.view.addSubview(imageView)

4，从网络地址获取图片

//定义URL对象
let url = URL(string: "http://hangge.com/blog/images/logo.png")
//从网络获取数据流
let data = try! Data(contentsOf: url!)
//通过数据流初始化图片
let newImage = UIImage(data: data)
let imageView = UIImageView(image:newImage);
self.view.addSubview(imageView)

5，使用图像控件实现动画播放
UIImageView 中提供了存储多张图片来创建动画的功能，具体做法是，在 animationImages 属性中设置一个图片数组，然后使用 startAnimating 方法开始动画，最后用 stopAnimating 方法停止动画。同时，使用 animationDuration 属性中可以设置动画每帧切换的速度（秒）。

import UIKit

class ViewController: UIViewController {

    var imageView:UIImageView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        imageView = UIImageView()
        imageView.frame=CGRect(x:20, y:20, width:100, height:100)
        //设置动画图片
        imageView.animationImages = [UIImage(named:"icon1")!,UIImage(named:"icon2")!]
        //设置每隔0.5秒变化一次
        imageView.animationDuration=0.5
        self.view.addSubview(imageView)
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        imageView.startAnimating()
    }
    
    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillAppear(animated)
        imageView.stopAnimating()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

6，保持图片比例 

imageView.contentMode = .scaleAspectFit