To aid in switching to other apps quickly, Apple adjusted the iPhone's functionality so that a double-tap of the Home button calls up an app switcher, featuring the four most recently used apps. A swipe on the touchscreen to the right right reveals audio controls and a screen rotation lock; a swipe to the left reveals more recently-used applications. Tapping and holding allows you to manually kill running apps, if you're so inclined.
With these seven services, Apple offers the multi-tasking basics iPhone users will want from third-party multitasking. Now it's up to developers to implement these changes in their apps.
Better application management
It's amazing how the addition of folders in iOS 4 can make the difference between a frustrating user experience and a pleasant one. Until now, users have been forced to launch applications by either swiping through pages of apps, or by resorting to a Spotlight search.
For my own part, I had 11 pages full of applications -- the natural limit of apps that can be displayed on the iPhone. Sometimes, different apps that did much the same thing each had a feature or two I really liked, but I had no way to group them together. As a result, they filled up all 11 pages -- crowding out other apps I might want.
With iOS 4, I've gone from 11 home screens to two, since I can now organize applications in folders, each of which can hold 12 apps. According to Apple, you can now house 2160 apps if you utilize all of the folder space. Now that the home screen is much more manageable, I have room to grow -- and I'm interested again in exploring new iPhone apps. And given that the App store now has more than 200,000 individual applications, the change is good for users and developers alike.
Apple's implementation of this feature is slick, yet obvious. To create a folder, tap and hold on an app icon until the apps begin to wiggle. Once in this state, drag and drop an app on top of another app, and a folder is instantly created, the iPhone background sliding away to reveal a storage area. Folders are automatically named using app genres, which you can modify.
One addition that would make this even better: an option to password protect folders. As much as I enjoy sharing my iPhone with curious passers-by or over-excited goddaughters, I would appreciate it even more if I knew certain data on the device couldn't be readily accessed by anyone poking around. Just sayin'.
Better Enterprise support
Apple continues to improve enterprise support with this update. Exchange 2010 now works with iOS 4, and the iPhone now can sync calendar, contacts and e-mail with more than one Exchange account.
Security has improved as well, as the iPhone now uses the device's passcode as an encryption key, and Apple has introduced new APIs developers can use that focus specifically on making sure private data stays private.
Also of note, iOS 4 allows enterprises to securely host and distribute in-house apps over the air without forcing users to connect with iTunes on their host computers. Another notable feature for enterprise users: support for SSL VPN security.
While iOS 4 still does not support FIPS 140-2-certified encryption (a standard some government agencies require), or over-the-air software updates (for better IT management), the iOS 4 enhancements will definitely be appreciated by IT departments. It's another step by Apple that could convince holdouts using the entrenched Blackberry platform that it's time to open up their systems to the iPhone.
The little things
iOS 4 is filled to the brim with small enhancements to the interface and built-in applications that will delight users. For instance, with iOS 4, the iPhone 3GS can now refocus video -- while recording -- with a simple tap on the screen. Tap-to-focus has been around for still photos since version 3, but the ability to refocus on the fly for video is a new feature for the iPhone.
Speaking of camera improvements, digital zoom has been enabled for use when snapping photos on older models, such as the 3GS. While a digital zoom is no substitute for optical zoom -- go too far and your pictures can get pixelated -- I'm willing to bet many users will find this truly useful.