With the release of iPhone 2.0 software, and especially the App Store, the iPhone has taken a significant step toward being a Mac "in your pocket," rather than merely a smart phone. While the emphasis here is on the benefits of being a Mac, there are a few downsides to consider. In particular, there are application crashes. While these unwelcome events happened occasionally even with iPhone 1.x, their likelihood has increased significantly with the explosion of third-party software now available.
With that in mind, here's a primer on how to navigate your way out of app trouble:
1. When to restart
One of the more common problems is that an application may start crashing every time you launch it, kicking you back to the Home screen. If this happens, it's time for some iPhone Troubleshooting 101.
Your first step should be (much like with a Mac) to restart the iPhone. To do this, hold down the Power button until the "slide to power off" option appears. Turn the iPhone off and then back on again. I have found that this cures about 90 percent of crash problems.
If the problem application has gummed up the works so much that the "power off" slider never appears, hold down the Power and Home keys simultaneously until the Apple logo pops up, signaling a forced restart of the iPhone.
2. Stay up-to-date
Most application crashes are the result (not surprisingly) of bugs in the application software. Hopefully, such bugs will be squashed in updated versions of the software that are eventually released. That's why it pays to check for updates.
To do a check from your iPhone, go to the App Store and tap the Updates button. If any updates are listed, you are given the option to install them.
Alternatively, you can check for and install updates via iTunes, by selecting Applications in the iTunes Library and clicking the "Check for Updates" button.
Expect some inconsistencies here. For example, in my most recent check for updates, two were listed in iTunes but only one was listed in the iPhone's App Store. Macworld's Jonathan Seff found other inconsistencies with iPhone app updates.
In any case, I recommend updating from iTunes (and syncing the updates to your iPhone) rather than updating from the iPhone itself. Installing software directly on your iPhone takes an inordinately long time. Making it more inconvenient, you should ideally refrain from doing anything with your phone while waiting for the update to complete. While the iPhone remains operational during an update, whatever you attempt to do will typically go at a slower pace, sometimes to the point that you may think your iPhone has stopped working, leading you to restart the phone. Impressively, the install process appears to survive such a restart and picks up where it left off. Still, matters will go more smoothly if you do your updating from iTunes.
3. Getting rid of apps
If an application continues to give you problems, you may choose to delete it. To do so, remove it both from your iPhone and iTunes before your next sync. Although Apple states that it is only necessary to remove an app from iTunes (which in turn should result in it being deleted from your iPhone during the next sync), many users have found that such "deleted" apps are transfered back from the iPhone to iTunes after a sync (without the warning message that is supposed to appear).
To remove an application from your iPhone, tap and hold on any application icon in the Home screen until the icons begin shaking. Now tap the X symbol in the upper left corner of the application icon you wish to delete. Then press the Home button.
To remove an application from iTunes, go to the Application window, access the contextual menu for the desired application and select Delete. Alternatively, with your iPhone connected, go to the iPhone's Applications tab. Assuming you are using the "Selected applications:" option, deselect the application you no longer want on your iPhone; this should prevent it from being put back on your iPhone without requiring that you delete it from iTunes.
Should you completely delete an application and later decide you want it back again, no problem. Just go to the iTunes Store and select to download it. If it is an a "paid app," the Store will remember that you previously paid for it and offer to download it for free.
Updated at 9:41 a.m. PT to correct the location of the X symbol for deleting applications. Also, these tips for dealing with buggy apps would apply to the iPod touch as well.