How can you see the value of a cookie on an iPhone?
You can't see cookie data on the phone itself, but if you activate Settings &gt; Safari &gt; Advanced &gt; Web Inspector you can connect the iPhone to an Apple computer with a cable and open Safari. Activate the Develop menu in Preferences &gt; Advanced &gt; Show Develop menu in menu bar

Now you can open a page on the iPhone and then select Develop &gt; your_phone &gt; the_page on the computer to see an inspector for the page on the phone. The second icon at the top is for storage and will show cookies for the page you show on the phone.

Sadly I can't find a way to show all cookies on the phone but if it is for development it is possible to monitor the cookie data.