3.4: URL schemes not working in built-in browser

jimrhiz

Thanks very much for the new release, @omz!

There seems to be an issue with pythonista:// and other URL schemes in the built-in browser. Consider this HTML file:

<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>Test URL schemes</title>
</head>
<body>
<h1>Test URL schemes in Pythonista 3.4 built-in web browser</h1>

<ul>
    <li><a href="https://google.com/">https://google.com/</a>
    <li><a href="pythonista://test.py?action=run">pythonista://test.py?action=run</a>
    <li><a href="shortcuts://">shortcuts://</a>
</ul>

</body>
</html>

It can be loaded into the built-in browser with

webbrowser.open(f'file:{path}')

where path is the full absolute path to the HTML file.

In Pythonista 3.3, all three links open: for the Google link, within the built-in browser; with the other two in the respective app. Further, if you long-press on any of the links, there is a popup previewing the URL with an action menu.

At 3.4, the Google link behaves as before. But the other two do nothing, either on a quick tap or a long press. This is on an old iPad running iPadOS 15.7.5.

I have an extensive web app within Pythonista that relies on the 3.3 behaviour. I hope there is a solution which will make it work again in 3.4, so I can upgrade my main iPad. I'd appreciate any suggestions.

cvp

@jimrhiz this works

webbrowser.open('shortcuts://')

Not sure you could use as workaround of your html way

I know that ObjectiveC SFSafariViewController allows to open https[s] only.

jimrhiz

Thank you for the reply, @cvp.

Right, webbrowser.open works with app URL schemes from within a running Pythonista script. But it does not help with calling apps from the HTML page that I construct and display in the built-in Pythonista web browser.

I know that ObjectiveC SFSafariViewController allows to open https[s] only

Is ObjectiveC SFSafariViewController the tool that implements the built-in web browser in Pythonista 3.4? If so, there must have been a change since Pythonista 3.3, because the built-in browser there was able to open schemes other than http[s].

Also, Safari itself can open app URL schemes, including pythonista:// for example, from a suitable web page. It puts up an annoying confirmation dialogue, which is one of the reasons I want to avoid it, but then it does goes ahead.

cvp

@jimrhiz said

Is ObjectiveC SFSafariViewController the tool that implements the built-in web browser in Pythonista 3.4

Pythonista doc, in "What’s New in Pythonista Version 3.4 " says

The in-app browser for the webbrowser module now uses WKWebView and has a new “Open in Safari” button

jimrhiz

Thanks for the information, @cvp.

This is also seems to mean that JavaScript no longer works at all in file: pages in the built-in web browser. If there's no workaround, it's a major loss of functionality.

cvp

@jimrhiz said

This is also seems to mean that JavaScript no longer works at all in file: pages in the built-in web browser

Why do you say that?

cvp

@jimrhiz you could try this

#import webbrowser
import os
import ui
path = os.path.abspath('a9.html')

#webbrowser.open(f'file:{path}')

wv = ui.WebView()
wv.load_url(f'file:{path}')
wv.present()

jimrhiz

@cvp asked

Why do you say that?

The reason I say JavaScript no longer works is this file:

<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>Test JavaScript</title>
    <script>
        alert("Hello world!")
    </script>
</head>
<body>
    <h1>Test JavaScript in Pythonista 3.4 built-in web browser</h1>
</body>
</html>

As before it can be loaded with webbrowser.open(f'file:{path}') . On Pythonista 3.3 the "Hello World!" message appears immediately, but on 3.4 it's not there at all.

Thanks for the ui.WebView idea. I'll experiment.

cvp

@jimrhiz ui.WebView uses the old (deprecated) ObjectiveC UIWebView class which is exactly what WebBrowser of Pythonista before 3.4 was using

And there, your JavaScript html works

omz

I made a last-minute change to use WKWebView instead of UIWebView for the in-App browser, and it looks like I forgot about some details.

Here's sort of a workaround, similar to the one @cvp suggested, but opening in a tab, like the built-in one.

import ui
import webbrowser
from urllib.parse import urlparse

class WebDelegate (object):
  def webview_should_start_load(self, webview, url, nav_type):
    if urlparse(url).scheme in  ['http', 'https', 'file']:
      return True
    else:
      webbrowser.open(url)

def open_browser(url):
  v = ui.WebView()
  v.name = 'Web Browser'
  v.delegate = WebDelegate()
  v.load_url(url)
  v.present('panel')

import os
url = 'file://' + os.path.abspath('test.html')
open_browser(url)

pleasehelp

@omz Back/forward button also sometimes wrongly disabled in builtin browser. You should update them by KVO observing the WKWebView’s canGoBack and canGoForward properties, not just every time a page is loaded, due to a new feature that allows back-forward buttons to work within single page navigation, by the JavaScript history API

jimrhiz

Great, @omz, thank you very much for this solution! It is working like a charm so far. I'm looking forward to upgrading to 3.4 on my main iPad soon.

Thanks also @cvp for helpful information and suggestions.