Judging an App by its Cover – Techniques and Tools for Creating and Testing a Professional App Icon

When I redesigned the KEYBOX icon for version 2.2, I promised to write about the icon design approach I took. It’s taken me some time to get around to it but here it is. In this post I want to talk about optimizing your app icon so that it has greater visual impact in the App Store. This is not an article showcasing a handful of awesome icons, there are already plenty of those.

The Basics

Most sales of iPhone apps are made via the App Store app present on each iPhone. When designing your app’s icon, how it will appear in this store is of utmost importance and as you can see from the image below, there are four important elements that introduce your app to the world…

  1. Icon
  2. App Name
  3. Price
  4. Review count and rating
App Slot


People are visual by nature. Our eyes are drawn naturally to images and shapes.

When an iPhone user is quickly scrolling through a list of apps in the App Store, an icon that grabs the user’s attention may be the only thing preventing the remaining three elements and most importantly your app’s detail screen from being overlooked.


Before & After

The old KEYBOX icon is an example of how not to design an icon. It was my first attempt at iOS app icon design and, admittedly, a bad one at that. As you can see from the below image, it was flat and almost the same color as the App Store background. It’s almost as if it were hiding from the iPhone user and in retrospect it’s a miracle KEYBOX sold any units at all prior to the icon redesign.


Below is the new KEYBOX icon.


I’m not claiming that it’s the most impressive icon out there but it’s a far cry from the original. I wanted to retain the spirit of the original icon (a secure place to safeguard your secrets) while also communicating how advanced KEYBOX actually is. Even though the image of a safety deposit box is familiar and trusted it was beginning to feel…. well, old.

The new icon keeps the signature keyhole (which has been there since the J2ME version back in 2005), and adds a foggy glass window through which we can just barely make out the many secrets represented by colored lights. The exterior of the box appears sturdy and the orange lit lock lamp communicates the box’s locked state. The grooved black panel rising slightly above the white box denotes that it is where the user unlocks the box. I could go on forever but what I’m getting at is the detail this icon now offers gives it a tangible feel and almost looks as if it could be plucked right out of the screen.


Real Testing

As you might have already guessed, when I redesigned the new KEYBOX icon I wanted to be sure it stood out from not only crowd but also the App Store itself. The most important advice I can offer in this post is this: From day one, understand how icons (not just your own) will appear in the App Store.

To demonstrate what I mean, the iPhone App Store (the native app, not the browser-based iTunes app page) offers two background colors, dark gray (#98989C) and light gray (#ADADB0). On the left, right and bottom sides of the icon is a drop shadow. Below is a blown-up image of the KEYBOX icon as it appears in the App Store. Compare it to the icon above and note the drop shadow on both sides and below the icon.

Drop Shadow Blown Up

Since translucency isn’t supported, you’ll need to emphasize your icon’s false sense of depth (the object casting the shadow) along these edges if you want a professional look.


Overcoming The Unnatural Icon

It should be obvious that an icon which doesn’t populate the bottom, left and right sides will look unnatural. We are forced to fill up those boundaries. I know I said this article wouldn’t be about existing examples of great looking icons but I just want to link to some creative icons that took this forced shape constraint and made something delightful with it. The lesson is let this constraint push you to be creative.


Porting Considerations

At some point you may want to port your app to the Mac, to Windows or maybe even to Android. At the time of this writing, iOS is the only platform that forces the rounded rectangle shape on us. If you’re porting your app away from iOS you’ll no longer be constrained this way. However offering the identical icon on a different platform can provide instant recognition with users already familiar with your iOS app so there is some merit in keeping the icon identical.


Standing Out

It goes without saying that you want people to notice your app. Once you have ensured that your icon fits well in the App Store you can now concern yourself with competing with other apps for attention. Below are some techniques other apps are already using. Your app icon should also follow suit.

  1. Using the drop shadow to provide depth.
  2. Using contrasting colors.
  3. Use alarming colors like red and yellow if appropriate.
  4. Using gradients to provide a sense of texture.

Below I’ll examine each of these techniques in detail…



As I mentioned earlier, people are visual and react to shapes and images. Objects that cast shadows appear to stand out. Since Apple renders a drop shadow under each icon we should use it by adhering to the rounded rectangle shape. The one element to be careful of is that this drop shadow also forces us to apply the correct lighting upon the object that is casting that drop shadow (from above, obviously). The only exception is when an icon is intended to be a flat window into a scene.

Another lesser used depth technique is the sink-into-screen icon.

Sunken Depth Icons

Apple’s Photo Booth and Newsstand apps are excellent examples of this. Rather than protrude out of the screen towards the user they sink into it. The Photo Booth icon cleverly uses a border to create a small booth/room and shows the floor to give a sense that it can be walked into. The Newsstand icon appears as the typical magazine stand one might find in a street kiosk. The only caveat with this approach is that it leaves less room for the objects within the sunken space. Lastly, a sense of depth can be achieved by casting inner shadows. KEYBOX’s black panel casts two such shadows onto the white box to which it is attached.

The worst way to destroy the sense of depth is to opt for Apple’s default glossy effects.  This effect encases your app icon in an chiclet-like button.  To turn this off, select “Prerendered” in the project’s Target Summary Window (near App Icons).  If you’re using a version of Xcode that doesn’t support this try setting the “UIPrerenderedIcon” preference to YES in Target Properties.


Contrasting Colors

The human eye is driven to contrasting colors. One of the best app icons※ to demonstrate this is the ever popular Temple Run by Imangi Studios. Its use of yellow and black helps it both stand out from the App Store’s gray background as well as pull the eyes of any iPhone user to it. Even if the game is not of interest to the user this icon simply cannot be ignored.

Temple Run App Icon

KEYBOX’s new icon also employs a contrast of white and black. The white contrasts with the App Store’s gray background and the black contrasts with the white.


Alarming Colors

Color psychology teaches us that some colors induce a sense of alarm in people. Red and yellow indicate spiciness, high temperature, danger, and even anger. Adding a white halo around these colors can amplify their effects. The topic of color psychology is too deep for this post but it is worth studying the effects certain colors have on a target audience and whether those effects are appropriate.



In reality, your app’s icon is a flat array of pixels. To provide the illusion that objects in your icon are tangible use gradients. They trick the eye into believing that light is refracting off surfaces at different angles, angles that should only be possible if the object itself were not flat. Take the aforementioned Photo Book icon’s red curtain. It appears to ripple but of course this is just an illusion.


The Tools & Techniques

We’ve discussed theory long enough. Now for some tools and techniques.

As you are probably aware, the App Store requires that you prepare your icon in a variety of resolutions…

  • 57×57 for non Retina display iPhones
  • 114×114 for Retina display iPhones and iPod touches
  • 512×512 for the App Store (will be resized at display time to a smaller size)

Obviously you won’t make the same icon 3 times but will instead resize it to each of these resolutions. Some people dabble only in raster graphics for this but I prefer vector graphics perfectly rasterized at the end to the right size.

I might be the only developer who isn’t using Photoshop / Illustrator to create app icons. I like to support Indie Developers and I’m an Acorn user. As for my vector graphics needs I discovered Inkscape and SVG years ago and never looked back. Inkscape is originally intended for Linux and on the Mac it has to run as an X11 application. This leaves a lot to be desired in terms of look and feel but it is a very capable SVG editor and gives me numerical precision over all my icons’ elements.

If you don’t spend much time doing graphics editing and don’t feel justified in forking over the amount of cash to buy Illustrator check out Inkscape. If you’re already in possession of Adobe software or any other software capable of the job by all means go with what you have.

I’ve prepared an Icon Template SVG file in Inkscape that provides the dimensions and rectangle rounded corners just the way Apple likes them. You can use this as a container for your icon and to export the various raster graphics at their respective resolutions. If you inspect the SVG XML you’ll find the exportable area to use with the “Export Bitmap” function. In this file I used a 512×512 rectangle with rounded corners (rx and ry set to 70.0).


A Modeling Contest

My approach for judging the visual appeal of my app icons is much akin to a modeling contest. Up until now I’ve made it sound as if creating an optimized app icon is down to a science. Nothing could be further from the truth. As if tweaking this or that element in isolation would eventually yield the perfect icon. Models in a beauty pageant are not judged in isolation, they are judged in tandem against one another, and so must our app icons!

The steps described below put you in charge of a modeling contest, for icons!

  1. Scour the iPhone’s App Store and take full 640×960 screenshots of screens with the most attractive icons you encounter.
  2. Of all these icons pick what you consider to be the best four. Any given App Store screen can only display five apps so yours will be the fifth competing for eye-balls against these four.
  3. Using Acorn, Pixelmator or any other graphics editor create a 640×705 image within which you’ll drop each 640×141 app slot.
  4. Place your app icon in the middle slot. If your app is not already available in the App Store you’ll need to get creative and override another app’s slot with your icon. Don’t worry about the app name or other text, we’re just concerned with the icon for the time being.
  5. Walk away from your Mac for at least 15 minutes and come back to gain a fresh and unbiased view. Remember, you want to see what App Store patrons who are otherwise indifferent to your app will see.
  6. Judge which icon is the most attractive.

At the end of this process, if your app icon doesn’t even come close to contending identify why that is not the case. From there, decide what actions to take in order to close the gap.

I’d love to provide you with a template full of beautiful icons against which you could compare your own but I don’t own the rights to those icons. I can only provide you with these instructions for creating your own template.

In Closing

Creating an app is no small task and takes weeks if not months from beginning to release. Regardless if you are selling your app or giving it away for free you want to get it into people’s hands and everyday it is getting harder to gain the awareness needed to accomplish this. Your app’s icon is the gateway to impressing potential users and you owe it to yourself to put as much effort into it as you did your app.

Speaking personally, KEYBOX’s sales have more than doubled in response to the new icon design. I wish I knew what I know now when I first released it. Hopefully you’ll be able to apply these techniques from the beginning for your app.


※Temple Run app icon used here with written permission of Imangi Studios.

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