title: How can I hide the WebView until the website's finished logining? [react native]
body: <p>I'm trying to make a component that display a website with <code>WebView</code> and then auto-fill the user information to login. I took care the auto-fill part by injecting some javascript into the <code>WebView</code> with the <code>injectedJavascipt</code> prop.  <br/>But the thing is I want to hide the <code>WebView</code> (the sign-in page), show a loading screen and only display it when the user is logged into the website. Since I can't interact with the website in any way, my workaround is to set the <code>flex</code> prop of the <code>WebView</code> to 0 and when the login complete, set it to 1 using <code>setNativeProps()</code>.  <br/>Is there anyway for me to know when the website has finished logining so I can then show the <code>WebView</code>? If not, is there any other way to hide my <code>WebView</code> and display it when that website's done logining?  <br/>tl;dr: basically i want my <code>WebView</code> to load some stuffs in the background while some loading screens are displayed and signal me when those things are done.</p>