The iPhone SDK: First Thoughts

Yesterday, Apple unveiled the software developer kit for the iPhone. A lot has been written about this already. As always, John Gruber has a comprehensive overview.

Here are my thoughts on this:

• First of all, interest in this seems to be tremendous. Yesterday, after the announcement, something happened which I’ve never seen before: Apple’s dev servers went down under the onslaught of interested developers.
• All iPhone applications will be sold through Apple’s store. There’s no other way to get on the iPhone.¹ Apple has some general rules about what applications they accept; the rules, however, are somewhat unclear. Apple has said that they won’t allow porn and malicious applications. Ryan Block asked whether they would allow SIM unlocking software. The answer, of course, was no. While it was fair to ask the question since it forced Apple to clearly come out against SIm unlocking software, I would have preferred if he had asked something a bit more interesting. For example, Apple has stated that their store is the only way to get software on the iPhone. Does that mean that a third-party application would not be allowed to install software? This question might seem a bit dumb at first, but package management systems like Fink or DarwinPorts are valid third-party applications which - on the Mac side at least - are even supported by Apple. Will they not be allowed on the iPhone?
• Will the iPhone Human Interface Guidelines be enforced, or are they optional? The guidelines say that “Only one iPhone application can run at a time, and third-party applications never run in the background.” This means something like an AFP server is out of the question. A specific iPhone application idea I’ve been contemplating is a kind of ad-hoc mobile social network. The application would periodically send your position to a server, and would then be able to tell you about people using the application near your location. Such an application would need to be running in the background; it seems Apple would not accept this.
• The application I mentioned above highlights another issue: Presumably, Apple will not allow demos which can be turned into full versions by directly buying a serial number from the developer since that goes around Apple’s store. Further, Apple will probably not allow software which is free by itself, but requires some kind of subscription that is paid to the developer.
• Seems Apple mainly spent the last year making formerly public APIs private. Compared to the “unofficial” SDK, Apple’s official SDK can do a lot less. This could mean two things: Either Apple doesn’t want developers to do the things they removed from the public API, or they aren’t yet happy with the interfaces and want to stabilize them before they make the applications public. Also, official third-party applications are forbidden from using private SDKs.
• I’m a registered SonyEricsson developer. Interestingly, just after the Apple event, SE started running a survey “on the quality and relevance” of their worldwide developer programs
• Finally, it seems I was right in my prediction that Apple will enforce compliance to API rules not through a sandbox, but through its approvement process.

All things considered, the official SDK is a mixed bag. It’s better than some people feared, but worse than some people hoped. Hopefully, Apple will open iPhone development further at some later date.

Further Reading

TidBITS has an extensive article on the subject, while Ars Technica provides a short summary. Macworld has some developer reactions, which typically range between “goodness” and wanting to kiss Steve Jobs “full on the mouth.”

March 7th, 2008 / Tags: Apple, iPhone, SDK, OS X / Trackback

iPhone Usability Study

inUse, a swedish usability firm, has published the results of an extensive usability study comparing the iPhone to three “traditional” cell phones. Unsurprisingly to everyone who has ever used one, the iPhone proves to be vastly superior both in user’s ability to complete tasks, and in user satisfaction. The iPhone’s success is mainly attributed to the fact users can directly manipulate objects on the iPhone’s screen. From the report:

What is it then that makes the iPhone different? Most importantly, it has removed one level of abstraction by allowing the user to act on objects using the finger directly on the phone’s surface.

Talking about the study, Jakob Nielsen writes in his newsletter:

Thus, I like to say that the iPhone is the “Macintosh” of mobile, because it’s the first mainstream direct manipulation UI with an interaction style similar to a mouse-driven GUI. Other phones are the “DOS” of mobile user experience, because they rely on keystrokes.

This study might seem flawed at first, because only a small number of people were tested. However, the study is sound since it is not a quantitative study. The goal here was not to create a statistical analysis of the tested interfaces; the goal was to find user interaction issues, and to compare the phones based on the issues found. Finding user interaction issues requires only a small number of test subjects. Here’s a graph from Jakob Nielsen, plotting number of test subjects vs. percentage of found usability issues:

As you can see, testing a given task with only 4 people will find around 75% of all usability issues in this task. Nielsen has an article explaining this phenomenon.

March 3rd, 2008 / Tags: Apple, iPhone, OS X, usability / Trackback

iPhone SDK Prediction

John Gruber has an article in which he talks about what Apple will announce on Thursday; specifically, what features the iPhone SDK will - or won’t - provide. He writes:

If it’s true that the dock connector is off-limits, that’s unfortunate, but also not surprising — clearly a big part of what Apple’s been working on in advance of this SDK are ways to sandbox applications for security and control of resources.

His suspicion that there will be a sandbox is based on this article by Jeremy Horowitz. But Horowitz writes:

Under current plans, SDK developers will be prevented from interfacing directly with Dock Connector-based accessories connected to the iPhone or iPod touch

He doesn’t explain how developers will be prevented from interfacing with the Dock connector. A bit further up in his article, Horowitz writes:

The most controversial aspect of Apple’s SDK plan is its intention to formally approve or deny all SDK-based software releases for its devices. Our sources confirm that Apple will act as a gatekeeper for applications, deciding which are and are not worthy of release, and publishing only approved applications to the iTunes Store

Personally, I find it unlikely that Apple created a sandbox for third-party apps. Adding sandboxes to existing environments is hard. Java’s sandbox was part of the design from the get-go; Objective-C, on the other hand, is basically C plus a bunch of features adding support for object-oriented programming. Attempting to sandbox C seems - at first glance - a bit futile.

In my opinion, a more likely solution to preventing stuff Apple doesn’t want is not through a sandbox, but through the approvement process. I would not be surprised if developers get full access to the iPhone’s APIs, but Apple will simply not publish software which doesn’t adhere to their guidelines.

On the other hand, sandboxing Objective-C is not actually impossible. One possible solution to sandboxing C in the iPhone would be to run third-party apps in a VM. Apple owns LLVM, which could possibly be used to sandbox Objective-C code in the iPhone. According to John Siracusa, Apple “recently did some extensive work on the LLVM ARM backend.” He suspects it’s because LLVM was used to improve performance on the iPhone; maybe it’s for the SDK?

We’ll see next Thursday, I guess.

March 3rd, 2008 / Tags: Apple, iPhone, SDK, OS X / Trackback