Open Source iOS CoverFlow Implementations

For my personal iOS development, I have a technical experiment and exploration todo list. It includes techniques I need to get better at, open source packages to investigate, that sort of thing.

I try to keep the items on the list small enough to do enough prototyping in a single evening to satisfy my curiosity. That way I am willing to move on during my next exploration session. The point is not usually proficiency, but enough familiarity to decide if the technique or framework merits further study. I often keep the code around as a reference, but it is definitely throwaway code, so it’s in a separate folder than “real” code.

One of the items on my list was to find and investigate CoverFlow clone examples floating around the intertubes. I found several that were based on Apple’s private APIs or were old enough that I was not interested. But, I did find two that I spent some time investigating.

OpenFlow, a CoverFlow clone developed during iPhoneDevCamp

The first was OpenFlow by Alex Fajkowski, released at iPhoneDevCamp in August, 2009. It is hosted on GitHub, but it does not look like it has been updated since then.

There is sample code included with the OpenFlow download, but it does not have a simple, quick-start example to get an initial feel for the package. Fortunately, others have written posts with some simple examples, two I looked at were:

A simple example by Julios Barros’ (@juliobarros).

And another simple example, but with more pictures and step-by-step details.

I liked OpenFlow well enough, but the current implementation did not allow for flicking through multiple covers. It behaves a little more like iTunes on the mac, not like browsing albums on the iPhone iPod app. Fortunately, my other “find” did have better flicking behavior, with tweakable momentum settings.

FlowCover, an easy to use OpenGL ES based CoverFlow clone

My other “find”, FlowCover by William Woody is essentially one OpenGL ES class with a simple helper class for data caching.

I like simple. Since I am likely to tweak the behavior of whatever I find, the simpler and cleaner the starting point — the better.

I added the two classes to my prototyping base project, and I was off and running. FlowCover works pretty much as expected, behaving smoothly and simply. The only change I made to FlowCover.m was to allow for different scaling when in landscape and portrait modes. Other than that, it worked just as I wanted.


If you are interested in adding some Cover Flow type behavior to your app, I recommend checking out both projects.

OpenFlow is based on UIKit, and has more features than FlowCover.

FlowCover is based on OpenGL ES, has few features, but behaves a little more like I expected Cover Flow on an iPhone to behave.

Either is a good choice, but my needs are simple enough right now that I think I will be using FlowCover.

As an indie developer, one of the best things you can do is to find like-minded developers that will provide encouragement and motivation while pursuing a commitment. A great collection of indie iOS developers have helped me stay on track, many of them are either developers associated with iDevBlogADay, or those I have met through the 360iDev conferences. I also encourage you to find local NSCoder nights, developer meetup groups, or other user groups to keep your motivation on track. If there aren’t any meeting locally, try to find one other developer and start one.

Also, here is a little more information about me, Doug Sjoquist, and how I came to my current place in life. You should follow me on twitter and subscribe to my blog. Have a great day!