Fix and prevent iPhone freezes and crashes

Editor’s Note: The following article is an excerpt from Take Control of Your iPhone, a $15 electronic book available for download from TidBits Publishing. All Take Control ebooks, including this one, are 50 percent off through April 29, 2008. The 195-page ebook helps readers understand what’s going on under the hood of the iPhone, with lots of tips for using the iPhone more effectively and an emphasis on troubleshooting assistance for solving problems related to activating, syncing, application crashes, iPhone freezes, handset security, and more.

Freezes and crashes are generic iPhone problems that can occur in any iPhone software, from Safari to Maps. In this excerpt from Take Control of Your iPhone, I cover iPhone freezes and crashes, explaining what’s going on, how to recover from them, and how to avoid them.

Note: Applications vs. Widgets: Each program on an iPhone falls into one of two categories: applications (Phone, Mail, Safari, and iPod) and widgets (the collection of items, from Text to Settings, that appear above the main four application icons on the Home screen). Apple refers to the latter category as both widgets and applications in its various documents. The main difference is that widgets tend to be smaller, single function programs (akin to Dashboard widgets in Mac OS X) while applications are more full featured (akin to programs in the Applications folder of Mac OS X).

A quasi-third option is currently the only option available for third-party developers to create software for iPhone: Web-based applications. These are run from Safari and are often referred to simply as Web applications.

Handle freezes

While running any of iPhone’s applications or widgets, your iPhone may suddenly stop responding to your touchscreen gestures. Even pressing the Home button produces no effect. Typically, any display activity, such as a Web page that is loading or a video that is playing, halts as well. When this occurs, the iPhone software has “frozen.”

Another symptom of a freeze is that the iPhone screen remains black, as if it is not turned on (although this symptom may also be caused by a “dead” battery).

To unfreeze an iPhone press and hold down the Home key for about six seconds. If this works, you are returned to the Home screen, with (hopefully) everything working again. If a force-quit fails to unfreeze the application, try further actions as described ahead in this section (begin with Restart, below).

Handle crashes

When you’re working with an iPhone application or widget, the iPhone may suddenly toss you back to the Home screen. When you return to the program you were using, you may further find that some of your recent changes have been lost. For example, a Web page that you had closed may now be back. When this occurs, it means the iPhone software has crashed.

After being dumped back Home, you should simply return to what you were doing and hope the crash does not recur. If the same crash does happen again (and sometimes again and again), try restarting your iPhone (described next). This often helps because many crashes are caused by a combination of events that won’t reoccur in exactly the same way after a restart.

Restart

To restart an iPhone, press and hold the Sleep/Wake button (the physical button at the top of the iPhone, next to the SIM card tray) until a red (and white arrow) slider (adjacent to the words “slide to power off”) appears on the screen. Drag the slider to power off your iPhone. Then press and hold the Sleep/Wake button again until the Apple logo appears. Wait a few seconds for iPhone’s startup sequence to finish, and you should be back at the Home screen.

While I refer to this procedure as a “restart,” some Apple documentation refers to it as a “reset.” I prefer “restart” both because it is consistent with the same action on a computer and because it avoids confusion with other meanings of “reset” for the iPhone.

Force restart

If your iPhone is really confused, even holding down the Sleep/Wake button may have no effect. In such cases, you can generally force the iPhone to restart by holding down the Sleep/Wake and Home buttons simultaneously for around 10 seconds.

Although I have seen no official confirmation of this from Apple, I expect that the difference between a normal and a forced restart is that the former restart is more “graceful,” making sure that all files that should be closed before restarting have done so.

iPhone crash data on your Mac

While the iPhone doesn’t provide feedback when it crashes, it does keeps track of the event behind the scenes. The next time you sync your iPhone with iTunes, you get a message that states: “Your iPhone contains diagnostic information which may help Apple improve its products.”

The message that appears in iTunes when you attempt to sync an iPhone that has had a crash since the previous sync.
This message means that one or more crashes occurred since your last sync. It three buttons:

  • Send to Apple: Click this button to forward details of the crash to Apple (hopefully helping them figure out the cause and how to fix it)
  • Don’t Send: Click this button to dismiss the dialog.
  • Show Details: Click this button to open a folder in the Finder where the crash data are stored: /Library/Logs/Crashreporter/MobileDevice/youriPhone .
    The exact contents of this folder depends upon the crash history for your particular iPhone. For example, if Safari has crashed, you’ll find a file with MobileSafari at the start of its name and .crash at the end (with numeric data in the middle). You can open the file in any text editor. Or, if you change the file’s extension to .log, double-clicking the file opens it in Mac OS X’s Console utility. It’s unlikely that you’ll glean much information from these files, but you may find a clue to the cause of a crash.

The crash dialog also has a “Do not ask me again” checkbox. Leave it enabled to avoid being told about crashes in the future. But what if you enable it and later change your mind?

You can reset it by Control-clicking (or right clicking) on the name of your iPhone in the Devices section of iTunes and then choosing Reset Warnings from the contextual menu.

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