iOS 8 Safari Action Extension; UIWebView Zoom, Scale, Scroll Position and JavaScript

For the upcoming action extension in Transloader, I’m using a UIWebView to show the webpage the user is currently browsing, so they can tap on a link they’d like to download:

UIWebView without zoomTransloader’s Action Extension, displaying a UIWebView

It’s nice, but I wanted to go an extra step. A user might zoom and scroll in Safari before launching the action extension and when they do, the web page would be shown from the top, not zoomed. Here’s how I changed that.

Context and Flow

One of the main purposes of an action extension is to allow a user access to functionality from a different app without a) leaving the current app and b) without leaving the current context (which is more or less the same, but context is the point I’d like to drive home with this post).

In that vain, I thought it would be neat to present the website a user was viewing in Safari the same way in the action extension – meaning the zoom level and scroll position.

I figured, a user browses a site, perhaps zooms in on stuff and when they find a link they’d like to download to their Mac, they press the Share button in Safari and select Transloader’s action extension.

The thing is, the UIWebView of the extension loads the website for itself again and hence starts from the top, not zoomed in. So the user is ripped out of the context, they’d have to scroll and zoom again to get to the same position they had in the Safari web view. I wanted to change that:
A user should see the same part of the website in Transloader’s action extension as the part they were viewing in Safari before tapping the Share button.

Luckily, Apple implemented a way that allows us to do just that.

Java Script Preprocessing

In an Action extension for webpages (action extensions that are displayed in the action sheet if the NSExtensionActivationSupportsWebPageWithMaxCount criteria is met), you can supply a JavaScript preprocessing file that will let you examine the contents of the webpage before your native code is called.

This way, we can extract the current page scale and the scroll position. Here’s how we do that. In the Action.js, we call our native code with these parameters:


– pageXOffset is the horizontal scroll value
– pageYOffset is the vertical scroll value
– pageScale is how far the user has zoomed into the page
– baseURI is the current URL displayed in Safari

With these parameters, we can do what we set out to do – display the web page in the Action extension the same way as the user left it in Safari.

In our implementation file, in the WebView’s delegate method “-webViewDidFinishLoad:”, all we basically need to do is apply these parameters to our own web view:

[self.webView.scrollView setZoomScale:self._pageScale

[self.webView stringByEvaluatingJavaScriptFromString:[NSString stringWithFormat:@”window.scrollTo(%ld,%ld)”,self._pageXOffset,self._pageYOffset]];

For a complete project of how this exactly works, please scroll down where you’ll find a Xcode Project on Github.

And this is what it looks like in action – notice that after the Action extension is tapped, the website appears the same way as it was in Safari:

UIWebView Zoom and Scroll in Action

Example Project

TL;DR – I uploaded a demo project here on Github.

I hope you can make good use of this code – and if you do, please be sure to let me know! 🙂

My name is Matt, I’m the developer of Eternal Storms Software. If you’d like to comment, you can catch me on twitter here: [twitter-follow screen_name=’eternalstorms’ show_count=’yes’] or by eMail.

Transloader Action Extension (iOS 8)

At the end of September 2014, I wrote about upcoming changes in Transloader for iOS.

Transloader iOS 8 Action Extension Icon

Today Widget

In that blog post, I wrote about a Today Widget that you could use to easily paste URLs you had copied to your pasteboard on iOS.
It would look like this:

I was pretty sure this would be the way to go, but after using it for a while and iterating on it, I became more and more convinced that this was not an optimal solution.

It’s not optimal for a couple of reasons.

– Although it’s far better than before iOS 8, where you had to open the Transloader app itself to get things going, the Today Widget approach is still a little cumbersome: copy the link, open Notification Center and tap the + button
– You’d have to do this for every link you’d like to add from a website, for example
– Doing that would erase your pasteboard contents you had copied before
– It takes you out of the app’s context

Action Extensions to the Rescue

So I started looking into Action Extensions. And now, this is possible:


Exactly. Instead of going back and forth to copy several links from a website to add to Transloader, it can all be done on the website itself.

If you’re on a file site itself (for example, you’re viewing a PDF in your browser), you can add it to Transloader more easily as well:



I think the combination of these two, the Today Widget (where you’ll still be able to paste links into Transloader, because I think it might still be useful to a lot of users) and the Action Extension will make Transloader very accessible and easy to use on iOS 8.

It will be available soon on the App Store.

My name is Matt, I’m the developer of Eternal Storms Software. If you’d like to comment, you can catch me on twitter here: [twitter-follow screen_name=’eternalstorms’ show_count=’yes’] or by eMail.

Making ZEN (Part 1)

[Note: This is a guest blog post written by my cousin, Sebastian Gansrigler, about the iOS game ZEN (App Store) he and I developed during 2014]

It was around March 2014, I started to set up a basic idea for a game I wanted to create in my spare time. How about combining a Rubik’s Cube and 3D game mechanics with complex mathematical theory and provide all of this with minimalistic pixel art on a touch interface? ZEN was born.

Basic concept on paper, pixel measurements, final screenBasic concept on paper, pixel measurements, final screen

I can’t really say where the idea came from, the game was always based on the concept of a rotating cube, about revealing something that’s hidden, about stress, learning, advancing and getting better and better by repeating it over and over again. ZEN was a good name: …a school of Mahayana Buddhism that developed in China during the 6th century. The word might be translated as something like “absorption” or “meditative state”.

Since I didn’t want to use any fonts, plugins or other preset assets, I created everything from scratch. Beginning with first scribbles on paper, I subsequently moved on to Photoshop and Illustrator to build a basic grid system, alignment rules, colors, etc. I tried to treat pixels like real pixels, there’s not one element in the game that’s round or off grid. Everything had to be perfectly consistent and at the end, of course, fun to play. From then on I went into After Effects for animations and interactions.

All game elementsAll game elements

One musician I had in mind for ZEN’s sound design was Brian Grainger aka Milieu. He created the original score for “Eufloria”, which I played a few years ago on PS3 and totally loved. I wanted something relaxing, yet stressful and packed with tension. Somewhere between Mount Kimbie, Kavinsky and Baiyon. I wrote him, Brian got on board and created an amazing soundtrack (soon available on his Bandcamp) and all sound effects.

Matthias Gansrigler, my cousin, has created some great apps for OS X and iOS, so I contacted him about the game. He did all the code and actual implementation of graphics and animations. The bug fixing was most fun, as soon as something had been fixed, something else came up. Special thanks to Das Möbel in Vienna for a great location to brainstorm and discuss (and of course for the ham & cheese toasts).

Funny button bugFunny button bug

After quite a bit over half a year of production, the game was completed and went online on December 21 2014 on the App Store for iPhone and iPad.

Sebastian Gansrigler is a 20-year old photographer and designer in Vienna, Austria. He works for WDM responsible for web and graphic design. You can reach him on twitter under @gansrigler.