title: iOS wkWebView, how to check when page jump
body: <p>I want to show the HTML title in navigation bar of the webpage and change the title whenever the page changes. I have tried to use the <code>didCommitNavigation</code> delegate method, but when a page request loads, the <code>didCommitNavigation</code> method may trigger multiple times. Is there another way I could check if a page changes?</p>