iPhone SDK Limitations: Multitasking, Java, Emulators

As people delve into the details of Apple's iPhone SDK, a few interesting issues are emerging. One developer guideline that is generating some concern is from Apple's Human Interface Guidelines for iPhone:

Only one iPhone application can run at a time, and third-party applications never run in the background. This means that when users switch to another application, answer the phone, or check their email, the application they were using quits. Its important to make sure that users do not experience any negative effects because of this reality. In other words, users should not feel that leaving your iPhone application and returning to it later is any more difficult than switching among applications on a computer.

To be fair, for most applications, this would be preferred behavior. There is no reason for Super Monkey Ball (for example) to continue running in the background, using up CPU cycles and Memory. Instead, as Apple suggests, the current state should be saved and returned when the application is relaunched.

However, this has raised concerns about the feasibility of an application such as AOL's AIM client, which typically does run in the background to alert the user of incoming messages. Based on one comment, however, this only appears to be a design guideline and not an absolute technical limitation:

I'm a programmer and I just tried it [using the iPhone SDK] and you can keep your app running in the background in the normal way ApolloIM and iFob do it. I.e. overriding applicationSuspend.

Another possibility could involve individual applications launching smaller background-tasks (daemons) short of full applications, but the feasibility of this is unknown at this time.

What this brings us back to is Apple's SDK license limitations and their editorial discretion with the iTunes App Store. From Apple's license agreement, this multitasking workaround is forbidden:

Applications must comply with the Human Interface Guidelines and other Documentation provided by Apple.

Even Sun's plan to bring Java to the iPhone is not technically allowed, despite their claims:

An Application may not itself install or launch other executable code by any means, including without limitation through the use of a plug-in architecture, calling other frameworks, other APIs or otherwise.

This could also restrict announced plans for a PC emulator for the iPhone.

It's still too early to say how strictly Apple will enforce these restrictions when approving applications for the iTunes App Store. By serving as the sole distributor for iPhone applications, Apple understandably wants to restrict malicious applications, but whether these limitations begin to encroach upon genuinely useful applications remains a concern. Apple's iTunes App Store launches in June 2008 alongside the new iPhone 2.0 firmware.

Related Forum: iPhone

Popular Stories

iPhone 17 Pro in Hand Feature Lowgo

iPhone 17 Pro to Reverse iPhone X Design Decision

Monday July 7, 2025 9:46 am PDT by
Since the iPhone X in 2017, all of Apple's highest-end iPhone models have featured either stainless steel or titanium frames, but it has now been rumored that this design decision will be coming to an end with the iPhone 17 Pro models later this year. In a post on Chinese social media platform Weibo today, the account Instant Digital said that the iPhone 17 Pro models will have an aluminum...
iphone 16 pro models 1

Here's How the iPhone 17 Pro Max Will Compare to the iPhone 17 Pro

Saturday July 5, 2025 1:00 pm PDT by
Apple should unveil the iPhone 17 series in September, and there might be one bigger difference between the Pro and Pro Max models this year. As always, the Pro Max model will be larger than the Pro model:iPhone 17 Pro: 6.3-inch display iPhone 17 Pro Max: 6.9-inch displayGiven the Pro Max is physically larger than the Pro, it has more internal space, allowing for a larger battery and...
iOS 26 Feature

Everything New in iOS 26 Beta 3

Monday July 7, 2025 1:20 pm PDT by
Apple is continuing to refine and update iOS 26, and beta three features smaller changes than we saw in beta 2, plus further tweaks to the Liquid Glass design. Apple is gearing up for the next phase of beta testing, and the company has promised that a public beta is set to come out in July. Transparency In some apps like Apple Music, Podcasts, and the App Store, Apple has toned down the...
imac video apple feature

Apple Launching These 15+ Products Later This Year

Sunday July 6, 2025 8:05 am PDT by
The calendar has turned to July, meaning that 2025 is now more than half over. And while the summer months are often quiet for Apple, the company still has more than a dozen products coming later this year, according to rumors. Below, we have outlined at least 15 new Apple products that are expected to launch later this year, along with key rumored features for each. iPhone 17 Series iPho...
iPhone Car Key Kia

Here's Which Vehicles Offer iPhone Car Keys

Sunday July 6, 2025 3:03 pm PDT by
In 2020, Apple added a digital car key feature to its Wallet app, allowing users to lock, unlock, and start a compatible vehicle with an iPhone or Apple Watch. The feature is currently offered by select automakers, including Audi, BMW, Hyundai, Kia, Genesis, Mercedes-Benz, Volvo, and a handful of others, and it is set to expand further. Apple has a web page with a list of vehicle models that ...
iPhone 17 Pro in Hand Feature Lowgo

iPhone 17 Pro Coming Soon With These 14 New Features

Friday July 4, 2025 1:05 pm PDT by
Apple's next-generation iPhone 17 Pro and iPhone 17 Pro Max are just over two months away, and there are plenty of rumors about the devices. Below, we recap key changes rumored for the iPhone 17 Pro models. Latest Rumors These rumors surfaced in June and July:Apple logo repositioned: Apple's logo may have a lower position on the back of the iPhone 17 Pro models, compared to previous...
iphone 17 pro render majin bu

New iPhone 17 Pro Renders Highlight Apple Logo and MagSafe Design Changes

Sunday July 6, 2025 8:43 pm PDT by
New renders today provide the best look yet relocated Apple logo and redesigned MagSafe magnet array of the iPhone 17 Pro and iPhone 17 Pro Max. Image via Majin Bu. Several of the design changes coming to the iPhone 17 Pro model have been rumored for some time, such as the elongated camera bump that spans the full width of the device, with the LiDAR Scanner and flash moving to the right side. ...
iPhone 14 Pro Dynamic Island

iPhone 17 Models Rumored to Feature Redesigned Dynamic Island

Monday July 7, 2025 7:38 am PDT by
iPhone 17 models will feature a redesigned Dynamic Island user interface, according to a post today from Digital Chat Station, an account with more than three million followers on Chinese social media platform Weibo. The account has accurately leaked some information regarding future Apple products in the past. The account did not share any specific details about the alleged changes that are ...