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Since it was suggested I figured I might as well start a thread addressing the common issues that newbies seem to be encountering with iOS 4. So let's hit briefly on the major topics:
Should I upgrade? This seems to be a popular question, and the answer is: There's little reason not to. It's free upgrade for all iPhone and iPod Touch devices, second-generation or newer, and at the very least, you'll get folders. Folders alone make this upgrade worthwhile as it allows you to organize and clean up your device, reducing the clutter and making things easier to find without having to flip through so many pages. I went from 11 pages down to 2-1/2, and it's made a huge difference in ease of location and access and the tidiness of my device. There's now a place for everything and I have it all organized and categorized nicely.
But if that's not enough you'll get other neat features like faces/places (for iPhoto users on the Mac), album art in album view, on-device playlist creation, the ability to turn off data roaming (I know at least one person here really wanted that feature), persistent Wi-Fi (no more disconnects) and more. And if you're a 3rd gen Touch or iPhone 3GS user, you also get home screen wallpaper and multitasking.
There are a very few compatibility issues that I and others have run across, but the vast majority of apps should work without a hitch, and those that don't likely will receive updates soon.
So yes. You should upgrade.
Upgrading Before you upgrade, be sure to run a backup: Right-click on your device in the left pane in iTunes and select "Back Up." Let it do its thing. It may take a while, so go grab a bite, a beer or read the forums or something.
When it's done, click the Check for Updates button and download iOS 4 (if you haven't already) and let iTunes install. This should be a completely automated process for Windows and Mac users, and for me took about 10-15 minutes from start to finish.
Creating Folders Now that you have a shiny new iOS 4 device, you're probably going to want to clean things up. Creating folders is simple: Tap and hold until the icons shake as usual, and then just drag one icon on top of another. The "bottom" icon should enlarge to indicate that you're creating a folder. Once you release the icon a new folder will created and named based on the App Store category it belongs to. You can change the name if you like. You should probably drag one app onto a related app just for the sake of organisation, but what you put in folders is really up to you.
Anything placed in a folder can be removed by opening a folder, tapping and holding until the icons shake, and then dragging outside the folder. You can release it back on the springboard, or proceed to drag it into another folder if you like. If you drag the last app out of a folder, the folder will disappear.
Multitasking (3rd gen Touch/3GS and iPhone 4 only) Multitasking is largely transparent, but you should pay attention to what's running. Double-tapping the home button brings up the task bar from the bottom. Swiping left will reveal your iPod controls, while swiping right will page through active tasks (assuming you have more than 4 open). This task bar can be accessed from anywhere, within any app.
However, contrary to what some seem to think, multitasking is not automatically active for every app. Apps have to be written to support it, and apps that are not will not resume where they left off if you switch tasks; they will reload the same as if you'd pressed the home button. There are very few apps at the time of this writing that support it, but within the next few weeks and months we will likely see a flurry of apps updated to do so.
When an app that's written to support multitasking is running, keep in mind that it takes up memory even when you're in another task, and you only have so much of it to go around. 3rd gen Touches and iPhone 3GS have 256MB, while the iPhone 4 has 512MB. 2nd gen devices only have 128MB, which is why they do not support multitasking.
With that in mind you should close any tasks you aren't currently using. To do that, with the taskbar open, tap-and-hold until the icons shake, just as if you were going to move icons around or create folders, and tap the red - badge to close the app.
REMEMBER: Every single app you open will remain in the task list until you close it, or the device closes it for you. (iOS 4 will arbitrarily and automatically close the oldest task if it runs out of memory while opening a new one. If you want to exercise control over which tasks you want closed, be sure to keep your tasks to a minimum and only keep those open that you'll be needing quick access to, or that you are currently using.)
Home Screen Wallpaper (3rd gen Touch/3GS and iPhone 4 only) I'd like to get this out of the way right now because there are a few who actually believe this: Black backgrounds do not save battery life. Putting wallpaper on your home screen will not decrease battery life. LCD screens don't work like that, and it's the backlight that's the real drain anyway, and you can't selectively turn bits of that off.
With that out of the way, I'm sure you're all familiar with changing your lock screen wallpaper. Well, adding home screen wallpaper works pretty much the same way, except that when you finally move and resize, you'll be given a choice of whether to set the wallpaper as home screen, lock screen, or both.
Okay, so why don't 2nd-gen devices get home screen wallpaper? Because those devices only have 128MB of RAM to play with, and with apps as memory hungry as many of them are, they need every kilobyte they can get, and homescreen wallpapers consume 2.4MB when uncompressed for display. (320x480x16)
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