UPDATE (10/08/2013): The cellular download limit is now 100MB. However, you can still use the tips below if you need to get your app under the new limit.
It may be difficult to keep your iOS app under 50 MB, but doing so can have big rewards. If an app is over 50 MB, it will have to be downloaded over a WiFi network. This means that if someone is bored and looking for a new app while away from their home or office network, they will not be able to do so and you just lost out on another download.
But is it really possible to get your app under 50 MB? It depends on your app, but if your app is over the limit, this post will show you the easiest ways to slim it down.
Depending on what you are already doing to optimize the size of your app, using these techniques can create some dramatic improvements. There are different ways of reducing the size of your app, but we want to focus on the ones with the biggest impact, with the least amount of work.
Usually, the biggest culprit when it comes app bloat is the images that you use in your app. Since PNG is the preferred format for iOS apps, let's take a look at a few ways that we can optimize them.
Xcode does do image optimization during the build and that may be enough to get an app under the 50 MB limit. But if you are looking to squeeze even more space out of your images, there are tools such as PNGOUT or ImageAlpha + ImageOptim. According to a case study on the ImageOptim site, they were able to reduce the images in the Tweetbot app from 26 MB down to 9 MB.
If you are creating a 2D game, then you want to be sure to combine your images into sprite sheets. Ray Wenderlich has a great tutorial on how to use Texture Packer with Cocos2D, if that is what you are using for your game.
Finally, reducing your image size could be as easy as saving your images in Photoshop using the File --> Save For Web & Devices feature. With this and the other image optimization tips, be sure to check the quality of your optimized images before implementing in your app.
The next thing that you can look at is your sound files, if you are using a lot of them. This is especially true for games.
Are you using stereo audio, when there are times that you can get away with mono? Does the MP3 version of your audio sound just as good as the AIFF version? If the smaller version of an audio file sounds just as good, it can be a pretty big reduction in the size of your app.
When someone sees that your app can be bought once and downloaded on both their iPad and iPhone, that is definitely appealing. But this also adds a lot of size to your app, especially since you have to account for the Retina display on the iPad.
If you are finding it especially hard to make your app universal, consider creating two different versions. Yes, your app may lose some appeal, but it will probably help you get more impulse downloads.
To make up for the separate versions, you may want to make your app free, with in-app purchases. It just depends on the type of app you have and your monetization model. If you truly cannot make your app any smaller, then creating separate versions for the iPad and iPhone is really the only way to go, if you want to stay under the 50 MB limit.
If you have an iOS app that is over 50 MB, you are losing out on downloads because buyers will have to wait to be on a WiFi connection to download it. After implementing these tips, hopefully you will be able to get your app under the limit. One final note: if you do implement these changes, be sure to test your app thoroughly before submitting your update.
Do you have any other tips for reducing the size of an app? Let us know in the comments below.
Photo Credit: iPad and iPhone