The iPhone App Store launched 15 years ago, and transformed the way that we make, use, and obtain software. More personally, it had a tremendous positive impact on my life. I had one of the first 500 applications that launched with the store that day, an open source 3D molecular modeler called Molecules.

With the launch of iOS 7, and its use of blurs throughout the interface, there's been a lot of interest in fast ways of blurring content. GPUImage has had a reasonably performant, but somewhat limited Gaussian blur implementation for a while, but I've not been happy with it. I've completely rewritten this Gaussian blur, and it now supports arbitrary blur radii while still being tuned for the iOS GPUs. At higher blur radii, I'm slower than Core Image, though, and I don't quite understand why.

It's been a little while since the last update, but version 2.1 of Molecules just went live on the App Store. 2.1 adds full support for the new Retina iPad, and has an enhanced rendering engine to support the detail on that newer device. I've also improved the contrast slightly on newer devices.

I'd like to introduce a new open source framework that I've written, called GPUImage. The GPUImage framework is a BSD-licensed iOS library (for which the source code can be found on Github) that lets you apply GPU-accelerated filters and other effects to images, live camera video, and movies. In comparison to Core Image (part of iOS 5.0), GPUImage allows you to write your own custom filters, supports deployment to iOS 4.0, and has a slightly simpler interface. However, it currently lacks some of the more advanced features of Core Image, such as facial detection.

Last week, Apple unveiled two new education-related products: iBooks textbooks and the new iTunes U courses. While both interest me, I was particularly fascinated by the new iTunes U courses and how they bundle information together. I converted my existing Advanced iPhone Development iTunes U class into a full course (which you can subscribe to for free) a few days ago. I wanted to write about what I learned in the process of doing this.

Yet another update for Molecules is now live on the App Store, this time version 2.02. The focus of this update is performance, and the new version greatly improves the speed of the new rendering engine. The 3-D models are now rendered at 3-6 times the speed that they were in the previous version, which should make previously choppy framerates on the iPad 1 much smoother. If you're interested in how this significant optimization was achieved, check out my question about it on Stack Overflow. Thanks go out to Tommy and Pivot for pointing me in the right direction on this.

A minor update to Molecules, version 2.01, is now on the App Store. This new version fixes some slight bugs with the new rendering engine in 2.0, including a case where the ambient occlusion shading for a model would sometimes appear too dark, as well as some odd glitches when using pinch zooming on a model.

The 2.0 version of Molecules brings with it a brand new rendering engine that utilizes OpenGL ES 2.0 to deliver realistic 3-D representations of molecular structures. This is a long way from the original OpenGL ES 1.1 renderer that I first wrote about here, so I want to describe in detail how this new version works. The source code for Molecules is available under the BSD license, so you are free to download the project from the main application page and follow along as I walk through the process.

A major new update to Molecules, version 2.0, is now live on the App Store. This version brings an all-new renderer for newer iOS devices, one that is capable of beautiful, realistic 3-D graphics. You are now able to search the NCBI PubChem database of small molecule compounds, something people have been asking for since the launch of the application. In addition to this, the interface of the application has been streamlined and particularly improved on the iPad. As always, the latest source code of Molecules is available for download.

A new version of Molecules is now available on the App Store. This adds iOS 4.0 multitasking and Retina display support, and fixes a number of issues that users have identified.

Last quarter, Dr. David Fisher taught an introductory course on iOS development at my alma mater, the Rose-Hulman Institute of Technology. He's made that course publicly available, including videos of the sessions, assignments, and tests. If you want, you can also grab the videos from his podcast on the subject.

I've been invited to give a talk at the SecondConf developer conference in Chicago, and I'm writing this to accompany it. I'll be talking about using the GPU to accelerate processing of video on Mac and iOS. The slides for this talk are available here. The source code samples used in this talk will be linked throughout this article. Additionally, I'll refer to the course I teach on advanced iPhone development, which can be found on iTunes U here.

Pi Cubed Lite, the free version of Pi Cubed, has been updated to version 2.0. This new version is now available for download from the App Store. The new version brings many of the enhancements from Pi Cubed 2.0, such as a undo / redo support, unlimited saved calculations, a cleaner interface, and Retina display and iOS 4.0 support. This new version of Pi Cubed Lite does not have the iPad interface that the full version does, nor the built-in and custom equation library capabilities. Additionally, Pi Cubed Lite now serves iAds within the application and requires iOS 4.0 to run.

Version 2.01 of Pi Cubed is now on the App Store. The newly released version 2.0 had a bug where a specific type of equation was not being migrated properly to the new data model, leading to crashes on startup for some users when they upgraded. Thanks to David Kinney and the App Store review team's prioritizing of the bugfix review, I was able to push out this version fairly rapidly to deal with this issue. I apologize for the problems it caused and for somehow missing this during my extensive testing.

After an embarrassingly long time in development, version 2.0 of Pi Cubed is now on the App Store. The big new addition in this version is an iPad interface (free for paid users as part of a universal iPhone / iPad application), but this release also brings undo / redo throughout the application, a revamped user interface, and other tweaks.

The videos of the Advanced iPhone Development class I taught this past semester at the Madison Area Technical College are now available for free on iTunes U. These videos amount to over 35 hours of HD content, covering more advanced iPhone development topics such as Core Animation, multithreading, Quartz 2-D drawing, and OpenGL ES. The course notes that accompany the class are available for download here in VoodooPad format, or for viewing here in HTML. Links to all sample applications used for the class are present in the notes.

A new version of Molecules is now available on the App Store, and the available source code has also been updated. Â The new version fixes a potential crash in iPhone OS 4.0 and adds a new means of directly installing molecular structures in the application.

Chicago hosted a satellite location for iPadDevCamp this weekend, and I had just as much fun as the iPhoneDevCamp I attended there two years ago. I had the privilege of speaking about Core Animation there, a talk where I crammed too much information into a one-hour space. My Keynote presentation is available for download here. The source code for the sample applications I showed off, NanoSpores for iPad and ReplicatorDemo for iPad, is also available for download.

You might have noticed that I updated Molecules to make it version 1.4, which adds some rendering enhancements and bug fixes for PDB searches. However, the highlight of this release is the addition of an iPad-specific interface. Additionally, now that iPhone OS 3.2 is publicly available, I have released the source code to the universal iPhone / iPad version of Molecules.

For those of you in the Madison, WI area, I thought I'd let you know about a course that I will be teaching next semester called Advanced iPhone Applications Development. The course will take place Wednesday nights at the Madison Area Technical College (MATC).

After a long hiatus, I've finally updated Molecules. Version 1.3.2 is an update focused on performance, with few new features (much like a certain OS version). Rendering speed has been nearly doubled, larger structures can be displayed due to memory optimizations, and a faster search interface is used when communicating with the Protein Data Bank. As usual, the source code for this version is available.

TheAppPodcast.com has posted a video review of Pi Cubed, which explores the features of the application from a layman's perspective. As a disclaimer, I commissioned the review, but the reviewer has been honest about other applications that he's looked at. It's worth viewing if you would like another perspective on the application.

Hot on the heels of the Pi Cubed Lite release is the 1.11 version of the full Pi Cubed. This version fixes some bugs in the 1.1 version that were pointed out by users and in iTunes reviews. Additionally, this is the first version of Pi Cubed to require iPhone OS 3.0, because I've started to integrate some 3.0-specific features. As usual, the updated version can be found on the App Store.

Since its April release, Pi Cubed has been well-received. However, it is difficult to sell users on the value of a $9.99 visual math tool in the App Store without any means for them to try it out. Well, I'm happy to announce that the free Pi Cubed Lite is now available on the App Store.

The good people at 148Apps.com have just posted a positive review of Pi Cubed. Honestly, using Emoji for a custom variable is not something that is part of my standard testing procedure.

Pi Cubed version 1.1 made it on the App Store today. This is a significant update, adding one of the major features that I had planned for the application: the ability to create your own custom equations and save those equations within your own equation library. It also adds support for plotting equations by handing them off to Grafly, if you have that application installed on your device.

We're coming up on Apple's Worldwide Developer Conference (WWDC) once again, and I'll be there like I was last year. I'm looking forward to meeting all the people I've been introduced to online since I launched my little software company last year.

Pi Cubed version 1.01 just arrived on the App Store yesterday. This is mainly a bugfix update, although a new editing capability has been added as well.

Today, I'm proud to announce the release of my latest application: Pi Cubed for iPhone / iPod Touch. Pi Cubed is a visual math application built around the touchscreen of these portable devices. Rather than follow the standard design of calculators, with fixed buttons and a small LCD display, I wanted to try something new. Pi Cubed uses the full touchscreen to typeset and evaluate calculations, and it relies heavily on Core Animation to animate all of its operations.

I've been doing a lot of work with Core Animation lately during development of my next iPhone application, and I came across an interesting way to optimize OpenGL ES rendering that I thought I'd share. This small improvement yielded a 14-25% increase in the triangles per second I was able to push in Molecules.

Now that I'm back from the holidays, all immediate issues are taken care of here at work, and iTunes Connect is back up, I've submitted version 1.3.1 of Molecules for review (and updated the source code. This is a bugfix version, addressing the recent crashes when trying to search the Protein Data Bank. The PDB servers stopped responding to one half of the search query I was sending, which was a condition I had not anticipated, and Molecules would crash as a result. Unfortunately, until they fix the server response, the search results will no longer list the titles of molecules.

I thought I should let you know about a new application that recently appeared in the iTunes App Store called iMoleBuilder (iTunes link). It is a $12.99 molecular visualizer that also lets you construct molecules and save them to the device or an available FTP site.

Earlier today, I submitted version 1.3 of Molecules for review in the iTunes App Store. The major new feature that this version adds is the ability to download custom molecular structures. For those of you who can't wait, the source code has been updated .

Recently, I was given the opportunity to write an article about the educational applications of Molecules for the RCSB Protein Data Bank's fall newsletter. That article is now online, and I think it came out well. It's worth reading if you're interested in my thoughts about the scientific and educational applications of the iPhone / iPod Touch.

UPDATE 2: Perspective rendering has been added: see below for the details. UPDATE: 3-D scaling using pinch gestures has been added: see below for the details.

UPDATE: iPhoneLive has been postponed. That's a real shame, because I was looking forward to meeting many people there.

With the lifting of the Nondisclosure Agreement on the iPhone SDK, I'm pleased to finally make available the source code to Molecules. If you go to the main page for the application, you should now find a link to download the latest source tarball (for version 1.2) on the right-hand side. You can also download the source code here. I am working on migrating my personal Subversion setup so that you can check out the latest code and so that I can authorize contributors to commit fixes and additions.

I just submitted Molecules 1.2 for review in the App Store. Sorry it's taken me so long to get a new version out to you, but this version required a complete rewrite of a portion of the core code. I also have been distracted by a few things at my day job and some shiny new technology that I've been playing with.

This might be jumping the gun a bit, but I wanted to let you know that a new version of Molecules, 1.1, has been submitted for review for the iTunes App Store. Even though it will take a bit of time to be approved, I thought you might be interested in a preview of some of the new features in this version.

I had a great time at the satellite iPhoneDevCamp in Chicago, where I was surprised with the number of well-known (to me, at least) developers who are located in the area. Although the San Francisco outpost may have had more attendees, I'd argue that we had as good a technical and business discussion going. We certainly had better shirts (courtesy of Stand Alone).

It looks like things are settling down in the App Store, because Molecules 1.0.1 is now available for download.

I'm pleased to announce a product that I've been working on for a little bit: Molecules for the iPhone / iPod Touch. Molecules is a free 3-D molecular viewer for Apple's handheld devices which lets you manipulate DNA, proteins, and other biomolecules with your fingers. Using a single finger, you can rotate the molecules, and pinch gestures zoom in and out on the molecule. Moving two fingers at once pans across the molecule.

I am now back home in Wisconsin after attending the 2008 Apple Worldwide Developers Conference. As a first-time attendee, I wasn't sure what to expect, but this ended up being a great experience. From the things I learned, to the people I met, I consider it well worth the price of admission.