GIFWebViewController.swift

import UIKit
import AVFoundation
import ImageIO
import MobileCoreServices
import WebKit

class GIFWebViewController: UIViewController {

    var imageArray:[CGImage]!
    
    //フレームレート
    let frameRate = CMTimeMake(1,5)
    
    override func viewDidLoad() {
        super.viewDidLoad()

        imageArray = []
        //適当に入れておく
        for i in 1 ..< 3 {
            if let image = UIImage(named:"image\(i).png")?.cgImage {
                imageArray.append(image)
            }
        }
        
        makeGifImage { url in  //成功した時だけ
            let animationGifView = WKWebView(frame: CGRect(x:0,y:0,width:300,height:200))
            animationGifView.backgroundColor = UIColor.lightGray
            
            animationGifView.load(URLRequest(url: url))
            self.view.addSubview(animationGifView)
        }
        
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    
    func makeGifImage(_ completion:(URL)->()){
        //ループカウント　０で無限ループ
        let fileProperties = [kCGImagePropertyGIFDictionary as String: [kCGImagePropertyGIFLoopCount as String: 0]]
        //フレームレート
        let frameProperties = [kCGImagePropertyGIFDictionary as String:[kCGImagePropertyGIFDelayTime as String :CMTimeGetSeconds(frameRate)]]
        let url = URL(fileURLWithPath:NSTemporaryDirectory()).appendingPathComponent("\(UUID().uuidString).gif")
        guard let destination = CGImageDestinationCreateWithURL(url as CFURL,kUTTypeGIF,imageArray.count,nil)else{
            print("CGImageDestinationの作成に失敗")
            return
        }
        CGImageDestinationSetProperties(destination,fileProperties as CFDictionary?)
        
        //画像を追加
        for image in imageArray{
            CGImageDestinationAddImage(destination,image,frameProperties as CFDictionary?)
        }
        if CGImageDestinationFinalize(destination){
            //GIF生成後の処理をする
            print("成功")
            completion(url)
        }else{
            print("GIF生成に失敗")
        }
        
    }

}