ViewController.swift

import UIKit
import SafariServices
import WebKit

class ViewController: UIViewController {

    @IBOutlet weak var webView: WKWebView!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
    }

    @IBAction func openSafari(_ sender: Any) {
        let url = URL(string: "https://yahoo.co.jp")!
        UIApplication.shared.open(url, options: [:], completionHandler: nil)
    }

    @IBAction func presentSafariViewController(_ sender: Any) {
        let url = URL(string: "https://yahoo.co.jp")!
        let safari = SFSafariViewController(url: url)
        present(safari, animated: true, completion: nil)
    }

    @IBAction func loadWebView(_ sender: Any) {
        let url = URL(string: "https://yahoo.co.jp")!
        let request = URLRequest(url: url)
        webView.load(request)
    }
}