A number of users report crashes from various iPhone applications, both Apple-supplied and third-party. The most common iPhone crash is one where the application you are working in suddenly ceases operation, the screen momentarily turns black, then the iPhone home screen appears. In a slightly more serious manifestation, the crash will result in a complete freeze where the iPhone is unresponsive.

Sometimes, when an application crashes, it will refuse to properly launch thenceforth, crashing immediately after its icon is tapped.

Generally, one of the three following procedures will resolve this issue. Try them in order.

Full reboot Perform a hard reboot of your iPhone as follows: Turn the iPhone off completely, by pressing and holding the Sleep/Wake button (on top of the device) for a few seconds then slide the red slider. Turn it back on by holding the Sleep/Wake button until the Apple logo appears. This can clear potentially problematic data, preventing some crash-types.

Restore the iPhone Try performing a restore of your iPhone. Connect it to your Mac or PC and, in iTunes, click the Restore button under the Summary tab. Restoring the phone will erase contacts, calendars, photos and other data on the phone, but will restore automatically backed-up information including text messages, notes, call history, contact favorites, sound settings, widget settings, etc.

Reinstall the application

• Touch and hold any application icon the icons begin to shake.
• Tap the “x” in the corner of the application you want to delete.
• Tap Delete.
• Press the Home button.
• Download the application again, either from your iPhone or your desktop computer (there will be no additional charge for the redownload)

If an application freezes or becomes unresponsive, force-quit it by holding down the home button for several seconds. This can eliminate problematic or hung processes that might be draining the battery.

To prevent future crashes, keep adequate free space on the iPhone’s internal memory. Like its desktop relative Mac OS X, the iPhone’s OS X operating system needs some head-room on the internal flash memory in order to operate properly. Try keeping at least 10% of the total space free to potentially prevent some crashes in applications, freezes and other problems.

As a last resort, go to the Settings application, tap General then select the Erase All Content and Settings. This will delete all media and data on the iPhone, as well as recent calls, etc., and all other settings. If you perform this operation and stop experiencing crashes, you might have problematic data being synchronized to the iPhone that is automatically put back when the phone is restored. In this case, you might want to go to iTunes, select Preferences from the File menu, then iPhone and delete your backed up iPhone settings — this includes text messages, notes, call history, contact favorites, sound settings, widget settings. Again, one or more of these data might be problematic.

Finding out what caused crashes Just like Mac OS X, the iPhone generates crash reports when things go wrong. These files are sent back to your computer whenever the iPhone is connected and synchronized with iTunes. In Mac OS X, they’re located in /Library/Logs/Crashreporter/MobileDevice/.

You might find a variety of files here with different prefixes that end in .crash. For instance, files that start with:

• “Maps” indicate a crash in the Google Maps application
• “MobileSafari” indicate a crash in Safari for iPhone

Finding out what caused crashes Just like Mac OS X, the iPhone generates crash reports when things go wrong. These files are sent back to your computer whenever the iPhone is connected and synchronized with iTunes. In Mac OS X, they’re located in /Library/Logs/Crashreporter/MobileDevice/ under the name of your iPhone.

You might find a variety of files here with different prefixes that end in .crash. For instance, files that start with:

• “Maps” indicate a crash in the Google Maps application
• “MobileSafari” indicate a crash in Safari for iPhone

You can open these files with any text editor to view their contents. Let’s look at a crash report generated by AOL’s instant messenger client for the iPhone.

• Incident Identifier: 9AFE6F0D-8F0F-4C3F-97C0-C53728C06C24
• CrashReporter Key: 7fc1bd07059a19504f4e83afe1ba44d1146fd901
• Process: AIM [1193]
• Path: /var/mobile/Applications/10915669-D64C-4ABE-993C-A07C1E586808/AIM.app/AIM
• Identifier: AIM
• Version: ??? (???)
• Code Type: ARM (Native)
• Parent Process: launchd [1]
• OS Version: iPhone OS 2.0 (5A345)
• Report Version: 103

Process tells you the name of the application that crashed, and its process number (in brackets). Path tells you where in the iPhone filesystem the application that crashed resides. Parent Process This is usually SpringBoard, the iPhone’s application launcher.

As you can see, you’ll also be presented with information about the version of OS X currently being used by the iPhone, the date and time that the iPhone crash occurred.

Next you’ll see:

• Exception Type: 00000020
• Exception Codes: 0xdeadfa11
• Highlighted Thread: 0

This tells the user exactly what type of processor exception caused the crash.

Next you’ll see the backtrace, which shows, in reverse chronological order, the series of events that happened right before the crash in each thread, e.g.:

• Thread 0:
• 0 libobjc.A.dylib 0×300c8884 0×300bb000 + 55428
• 1 UIKit 0×30a9edd0 0×30a54000 + 306640
• 2 UIKit 0×30ab1990 0×30a54000 + 383376
• 3 UIKit 0×30aa6a0c 0×30a54000 + 338444
• 4 UIKit 0×30a80eb8 0×30a54000 + 183992
• 5 QuartzCore 0×31e875c0 0×31e7f000 + 34240
• 6 QuartzCore 0×31e874d0 0×31e7f000 + 34000
• 7 QuartzCore 0×31e9e92c 0×31e7f000 + 129324
• 8 UIKit 0×30a7e9b0 0×30a54000 + 174512
• 9 UIKit 0×30ab07cc 0×30a54000 + 378828
• 10 UIKit 0×30aa8da8 0×30a54000 + 347560
• 11 UIKit 0×30aa45ac 0×30a54000 + 329132
• 12 AIM 0×00003b0a 0×1000 + 11018

Now you know (in the above example) that the crash occurred while libobjc.A.dylib was being accessed, but before that came the UIKit process, and before that the QuartzCore process. You’ll see files with the dylib suffix often in crash reports. These are OS X dynamic libraries integral to core-level iPhone functions.

RIght now, the best use of iPhone crash logs is seeking of patterns. Look for the most commonly implicated applications and processes, then direct your troubleshooting techniques appropriately. Lots of SpringBoard crashes? Try a reset. Repeated Safari crashes? Clear the cache, cookies and history as aforementioned.

A secondary use is to look for data that might be implicated in the crash, then delete it as mentioned above in the Preventing Crashes section.

Also, remember that you can send these crash reports to Apple when your iPhone is connected, providing the IPhone software team with valuable data that might be rolled into a future update.

Source: iphoneatlas.com

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