iOS 4 introduced multitasking. Now you can run your favorite third-party apps — and switch between them instantly — without slowing down the performance of the foreground app or draining the battery unnecessarily.
Switch between apps quickly.
The multitasking user interface allows you to quickly switch between apps. Just double-click the Home button to reveal your recently used apps. Scroll right to see more apps, then tap one to reopen it. No need to wait for the app to reload.
And pick up right where you left off.
Apps can remember where you left off. So when you return to the app, you can jump right back into playing your game, reading the news, finding a restaurant, or whatever you were doing.
Listen to audio in the background.
Now you can listen to audio from compatible third-party apps while checking email, surfing the web, playing games, and performing other tasks. So when you want to follow a ball game or listen to music from Pandora, your productivity never skips a beat.
Get VoIP calls while using other apps.
Third-party apps such as Skype let you make voice calls over the Internet. Multitasking in iPhone 4 makes it possible to receive these Skype or VoIP calls while other apps are running, even when your iPhone is locked. And during a call, you can keep the conversation going while you switch to another task, such as checking a movie listing or reading an email.
Keep GPS apps running.
Apps that use GPS can continue to run in the background. Not only do they constantly update your position, they can also give you spoken turn-by-turn directions even as you listen to music (the music volume lowers while the directions are spoken). It’s perfect for social networking apps, too. Now you and your friends can find each other even when you’re not actively using the app.
Receive push and local notifications.
Third-party apps and services can send alerts and messages directly to your phone. So you can get sports scores, news updates, game requests, reminders, alarms, and more, without having to open the app that’s providing the notification.
iOS 4 makes it easy to leave apps without quitting, but what happens when you actually do want to terminate an application? Quitting applications can really help with older apps that have not been updated for iOS 4 “multitasking” and that do not properly return to the state they previously were in when resumed.
Removing the Application from the Recents List
The simplest approach for quitting apps is to use your recent app list. Double-click the home button to display the recently accessed applications. Press and hold any of the icons shown (taking you into “wiggly-mode”,) then navigate to the application you want to quit and tap the red circled minus button. This sends a signal to the application in question that allows it to quit. The application will be re-added to the recents list the next time you launch it.