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Where Corona SDK Falls (kinda) Flat


Update 10/08/2011:  Instead of making another post to highlight other issues with Corona, I'll just continue to update this article.

The Corona SDK is starting to become more and more popular among developers.  In fact, my tutorial on setting up Corona for Windows development is still the most popular post on this site.  Since I've posted, lots of other great game developers have been posting about Corona, along with Jesse Warden, who seems to have been making all sorts of contributions.  In fact here is a video from Jesse Warden that is almost 2 hours long, covering the process for developing in Corona (on a Mac).  Needless to say, there is lots of momentum and excitement surrounding Corona, and I'd say with good reason.  Corona is a great solution for creating games quickly, which will work on (most) Android devices and iOS.  Even with all of the Ant or Maven scripts in the world, it doesn't seem like there has been an easier solution made for cross-platform development yet.

(image credit: John W. Iwanski aka Chicago Man)

With all of this in mind, there are still a few things about Corona (aka Ansca Mobile) that seem to be counter-intuitive/counterproductive.   This criticism isn't meant to be stated matter-of-factly, so if any of these gripes are unwarranted, please let me know in the comments.  Here is another good blog post from a Flash/Corona developer which covers some of the same issues brought up in my article.

Android Support

The marketing copy on Corona's website states (emphasis mine) "Corona is the only complete solution for developing across platforms, OS versions, and screen sizes," but that's not entirely true.  Since Corona SDK's release #591, only Android OS 2.2+ and ARMV7 devices are supported.  This means there is a long list of fairly recent Android devices which cannot run apps made with Corona (the best list I could find of ARMV6 devices was here.  It includes HTC Aria, Hero, Legend, LG Optimus, Motorola Backflip, Samsung Galaxy, ViewSonic ViewpPad, ZTE Blade/San Francisco and others).  Not a deal-breaker, but it is worth mentioning, since Ansca Mobile doesn't make this very obvious on the website.  It also seems as though there will be no intention of adding support in the future.

Also, there are a few (somewhat important) features in Corona which only work for iOS.  For example, in the notes on, it mentions anything related to the device Camera or Photo/Media library is for iOS only.  Same goes for all of the map features - iOS only.  While this probably isn't a reason to look elsewhere, it might be.  Again, it's not overly obvious that Android isn't supported.

Response from Ansca Mobile:

As far as Android goes, everyone knows it's incredibly fragmented. There's tons of different devices, tons of form factors, versions, etc. Basically, in order to continue to move the product forward (in terms of Corona + Android), we had to draw the line somewhere. Android 2.2 and Armv7 just so happens to be where that line was drawn. For developers who absolutely need support for an old version of Android and anything below the Armv7 architecture, then Corona's definitely not for those developers.

Android Performance

All devices are not created equal.  Although the hardware specs for Android devices vary greatly (compared to iOS devices) the general consensus among the Corona development community is that on average, Android performance is worse than iOS performance when using Corona.  This is even highlighted by popular third-party library developers of Particle Candy and the Lime library.  The particle candy download page explicitly states:

please keep in mind that Corona may run slower on Android devices than on iOS devices. Also, not all of the SDK's features are available on Android devices yet. Ansca is working hard, however, to further improve both, performance and feature richness on Android devices.

The developer for Lime made a similar observation on the Corona SDK forums:

The main performance issues I find, which are certainly a lot more prominent on Android, are down to how many tiles ( or other Display Objects/Groups ) are active.

Here is a thread on the forums where you can see for yourself how this can be a headache to developers, and one without any obvious solutions other than waiting for Corona to improve Android performance.

Can't Trust Simulator Performance

This might seem obvious, since your development workstation is almost certainly more powerful (by a few orders of magnitude) than your mobile device.  You would expect a 64bit machine with 8gigs of RAM to outperform your phone, but it might not be obvious where the exact threshold is.  For example, just by browsing the forums there are many developers having issues with performance discrepancies between the simulator and devices (here is just one example).  Undoubtedly, there will always be developers having issues with something or another, and that doesn't mean it's the software's fault.  However, just about everyone that has done game development has run into performance issues at one time or another, and the typical remedy is debugging and profiling.  Both of which have very limited support right now (at least for windows).

This is further highlighted by a third-party Corona SDK library called Lime, which offers lots of helper classes and features.  Unfortunately, with some implementations there are hardware-related performance issues.  What's tricky is that it's not always obvious what the exact problem is - since some games work without issues.  When that's the case, everything is fine... but if you are having issues, you may find yourself tweaking code endlessly without any clear resolution.  Code that seems like it should work just fine (and appears to do so in the simulator) might not work on your device.

Again, this could all be code or game design related, but the fact that there are many developers having similar issues (and not a whole lot of answers) makes this noteworthy.

Response from Ansca Mobile:

... the other issues you have (such as inconsistent simulator/device performance, etc), all we ask is that if you find something, to please create a test case (a small example project that sort of reproduces and isolates the bug), and then submit a bug report. The bug base is engineering's "to-do list" so to speak, so that's definitely the fastest way to get something resolved. The bug reporter is here:

(When you log into your account on, you can click the 'Report a Bug' link at the top to get back to that page at any time)

Developer Support

Since this article was originally posted, the Corona forums have been updated to allow non-verified users read-only access to forums - also, by signing up and verifying an account (no subscription needed, trial users are ok) you have full access to read and post in the support forums.  This was perhaps main topics of this post, and the issue was completely resolved within a few days.  I believe that speaks volumes about the developer support Ansca Mobile provides for it's Corona SDK users, which is vital to a thriving new language / API / developer tool.


The debugger for Corona SDK leaves a lot to be desired.  It's basically a command-line debugger, so any debugging you do is done via typing actions  into a terminal/command prompt.  This is obviously a bit of a hassle when trying to debug, although better than nothing! (For a while, there was no debugging option for Windows).  There are often times you will just get a "run time error at Line ##," which is certainly helpful to track down where it's happening, but there's no other information given (e.g., what type of error was it?)

Lua Library Support

Corona SDK uses Lua for the scripting, then parses this into the proper formats on their servers during the build process.  This was a great idea, since Lua can be very powerful and flexible.  However, as another blogger pointed out:

Lua has a rich library of code available to it, but Corona will not work with any of the many binary libs. In our case, this lead to us having to abandon interfacing with a web service using AES encryption. In general, you are restricted to whichever advance features the development team have included and exposed. This includes OpenFeint, Flurry, and an older version of the Facebook Connect library. For Twitter or Facebook using OAuth you'll have to roll your own solution (unless I decide to share mine…).

Authorization Process

It's not unusual for software to limit the number of installations you can have across multiple machines.  Corona SDK limits you to 2 installs per license.  That means if you have a desktop and a laptop, all your installs are accounted for.  However, what if your desktop and laptop are both PC? You also need a computer running OSX to build for iOS devices, which would put you over the 2 machine limit.  Same for running a virtual OS, with a program like VirtualBox.  If you have Corona installed on your desktop, and within a VirtualBox instance, both of your licenses are used up, and you will not be able to install on any other machines or VirtualBox instances.

The only way to "deauthorize" a computer, is by selecting an option in the Corona Simulator on that computer.  Let's say you installed onto a VirtualBox instance which has since been deleted, or onto a computer which you don't have access to anymore, or one that has been reformatted.  Unfortunately, you are out of luck and the only solution is to fill out a support ticket - so that Ansca staff can manually remove authorizations.  As far as I know, there is no other way to deauthorize your machine.  As you can imagine, this has the potential to turn into a very long and frustrating process (link goes to Corona forums, in a thread where someone has this exact problem).

Long story short, you may want to plan out your development process and think carefully about how many machines or Virtual Machines you will need for development.

Limited Subdirectory Support

When working on any apps, not just games, the organization of your code and assets can be a huge factor in how efficient your development process is.  Unfortunately for Android developers, Corona does not currently support subdirectories for all of your assets, at least not in a very robust way.  That means most of your non-lua files (music, art, etc.) are all in a single folder.  This may not be a huge issue if the number of files in your project is small (less than 20), however it can become a nightmare for more complex projects.  Here is just a small example of how this limitation could get out of control.

note: This limitation was not obvious to me right away... the Corona Simulator seemed to allow subdirectories without any problems.  Issues only arise when you build the file and try to actually run on your device.

update:  Since build #619, subdirectory support is available for iOS apps, but still not Android.

Other Gripes

Honestly, there aren't too many other gripes I have about Corona.  It seems like the perfect solution when everything works according to plan, and when you only need to use the features that are supported.  If you venture into uncharted territory however, any troubleshooting or debugging could be entirely up to you.  The community is extremely helpful, as are the admins, but there does seem to be a slight element of luck/magic/voodoo surrounding performance.  Or maybe it's just a result of incomplete/insufficient documentation - either way, this small list of gripes encompasses the main issues I have noticed with Corona.  Feel free to add on if you have others, or if you have alternate solutions.

Follow up thoughts:

Another important thing to note is Ansca Mobile's quick response to community feedback.  It seems that whenever a blog/forum/etc. post is published anywhere online, Ansca Mobile staff are there to read it and provide responses within hours.  I mentioned to the staff in an email that  I haven't discovered a development community this enthusiastic since Actionscript 3 came out.  Most of the other write-ups about Corona SDK state similar things - and now that I have access, I'll be speaking with the rest of you Corona developers in the forums!  Special thanks to Hetal and Jonathan at Ansca Mobile for the feedback.  If anyone notices other mistakes/misunderstandings in this post, please let me know via email / comments!


Peach Pellen says:

Hi Thomas,

I was sad to read the above and wanted to post a little message to you.

Firstly, trial users can use the forums! There are a couple of private forums for subscribers only however the majority are public.

It sounds as though your account wasn’t properly activated for forum posting – however contacting support will get that fixed right up.

Secondly, I’d like you to know that you do NOT receive less support as a trial user.

I’m one of the main forum posters and 5/6 of the areas I focus on are open to everyone. (New Users, Game Dev, Dev Support, Device Builds and Bugs – all public!)

To me, it’s really important that everyone feels like they can get help if they need it – the idea of someone getting frustrated and upset (as I did, many times) while trying to learn the ropes is something I find genuinely distressing, not least because I remember how that feels.

I hope you will be a forum poster soon and will get to be a part of the positive community you describe in your final paragraph.

T says:

Thanks Peach, I do intend on being an active forum member, now that I have activated my account. Looking forward to seeing you there!

Walter Luh says:

Thanks for the feedback, especially the forum issues. Just wanted to let you know, this afternoon we fixed the forums so “unverified” user accounts now have read-only access to the forums, same as anonymous users.

T says:

You guys are great. I’ve updated the post to reflect this, and completely removed the section about the forums. Thanks for the quick resolution, I’m sure it will be a great change all around.

Joshua Quick says:

Hello Thomas,

You might be pleased to know that Ansca has recently added Camera and Photo Library support to the Android version of Corona.

Also, you were correct in stating that Corona’s min system requirements for Android was not easy to find. That was recently corrected. Ansca’s “Download” web page now documents the Android 2.2 ARM 7 min requirement.

T says:

Thank you very much for the update, and for being so attentive to the development community. This post is turning is slowly into a list of praises! :)

Luca Bazuca says:

Dear all,
I am on windows and need to develop for:
– android
– iOs
– blackberry
However I got the impression, that if I want to use Corona to build iOs, then I have to install it on a Mac. Would then be sufficient to transfer my code to the Mac to then automatically get the iOs for iPad/iPhone ?
My app is not doing anything particularly fancy, does not make use of audio or videos, simply a bunch of form-based user interfaces and HTTP POST operations, followed by XML parsing and some maths.

At the moment, I’ve got my app using eclipse and the AndroidSDK, and using the BlackBerry JDE, however it is not nice since I have 2 code bases.

Looking forward your reply.

T says:

That’s correct – to build for iOS devices, you simply need to install Corona SDK on a Mac, and export the same code. Actually, you can export to all devices you want on OSX (iOS, android, nook, etc.), it’s only the windows version of Corona that’s limited (in that it can’t export to iOS). I was in a similar boat using eclipse and multiple code bases. With Corona it’s much easier as long as you aren’t doing anything intensive with native functions.

rp3 says:

Hi Thomas,

Thanks for the great post! I am new to Corona SDK and done with some of the simple assignments on windows platform. Now I have to implement AES encryption. Trying Luacrypto lib. for the same, but could not able to work it in Corona.

Any help will be great for me.

T says:

Thank you, glad the article helps. Including 3rd party Lua scripts/libs does not always work in Corona. Do you know what part of the script isn’t working?

rp3 says:

Thank you, I did’t able to install luacrypto lib in Corona SDK. If any instructions to work with third party library (like Luacrypto) in Corona SDK on Windows platform will be helpful.

Craig Holm says:

I am emerging from my dusty Pascal/FoxPro/ANSI C daze to try my hand at app development. Just beginning to get my arms around Corona and Lua – bit of a learning curve. Have tried several times in trying to coax the debugger to work – best I can get is:
dyld: Library not loaded: /usr/lib/libedit.3.dylib
Referenced from: /Applications/CoronaSDK/debugger
Reason: image not found
Seems to me like I haven’t installed everything I should have although I’ve got through the process a number of times. Any suggestions?

T says:

Usually when I run into that error, it’s due to the letter-case issues (e.g. if your code says “thisimage.jpg” but the filename is “ThisImage.JPG” then it will raise an error). Try double checking all your filenames first, since it seems like that might be the culprit. I know I’ve wasted lots of time with this same issue, just because I forgot that a file was CamelCased, or because the extension was uppercase, but in code it was lower.

open768 says:

yeah some issues with the corona sdk, but then you got to take the good with the bad – there is no such thing as perfection – despite what the marketting may say.

The arm6 issue is a still a massive one as its being used in newer handsets too – presumably to keep costs down. There is no good reason for ansca to cut this treasure trove of revenue away from developers.

I actually like the corona product and am committed to building my first game in it – but because of these restrictions when it becomes successful the first thing I’ll do is port it out of corona to something that gives me access to a wider customer base.

Oh the license issue is a real problem. if you buy an android only license you get two seats , if you buy a ios only version you get two seats. But if you spend nearly double and get a combined IOS and Android license, you get… 2 licenses. yup you lose two seats when upgrading. I pointed this out to corona but they responded intransigently saying thats just how it is.

Other gripes in no particular order: no convex shapes in box2d – no micro-payments ability since they discontinued superrewards – no ability to manipulate pixels – functionality not supported in the simulator

Corona is a great product, but I just get the feeling they act like a microsoft. They need to care more about the developers rather than get defensive about criticisms.

Frankie says:

Hi, how did you “activate” your non-subscriber account? I’ve been developing on Corona for a few months now and have found the restricted forums to be high on my list of flaws. I’ve clicked around looking for a way to validate my existence or authenticate in some way, but it just keeps pointing me towards the paid subscriber route.

So how did you do it? I’m eager to get involved in discussion. :)

[…] been slowly finding  out more and more about problems with the Corona SDK, in […]

VRMan says:

My partner and I are enjoying Corona trial and the plan was to wait until the game was complete before subscribing. However, we’ve been using it for four months and there have only been the ‘daily build’ updates. How often if ever do they update the trial version?! We want to code with the latest, and it seems silly they won’t let the trial users do that.


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