The upgrade to iTunes 10.1 killed syncing my iPad. An 'Unknown error 0xE800000A' dialog was displayed. Searching Apple support, where the problem has occurred before without a fix beyond rebooting the device, and searching for the error on the web also didn't give a solution that worked.
Checking in the Console showed that iTunes couldn't write to a plist file in /var/db/lockdown; the file already existed and belonged to _usbmuxd. A quick Terminal session with:
sudo rm the file name
using the file name of the problem plist followed by a restart cured the problem.
[crarko adds: I haven't tested this one. I hadn't heard of this issue before but searching for it indicates it has affected a number of people, using any kind of iOS device.]
I've found that using the normal backlight of my phone is sufficient for a flashlight. But waking the iPhone (before unlocking it) only keeps it lit for roughly 6 seconds and having to fully unlock it with a passcode takes too much time -- not to mention it requires looking at the phone.
I've always been a bit dumbfounded that flashlight apps exist for the iPhone (actually, not that they exist, but that people download them). The main reason is that whenever I need light, I need it quickly. Having to:
wake my phone
input a passcode
locate and launch an app
takes way too much time. Another reason is that for the average dark situation, simply having the screen lit (even if it's not pure white) generally suffices.
Unfortunately, when waking the iPhone, it only remains awake for a few seconds before going dark again. However, if you slide the slider to unlock it (even if you are prompted to input a passcode), it stays lit for a whole minute before sleeping.
So I've found that the fastest and most convenient way to use the iPhone as a flashlight (albeit a simple one) is to:
Click the 'sleep/wake' button
Slide the slider
This is half the steps required if you were to use an app, not to mention they can be done super quickly and without looking at the screen. And on top of all of that, as a bonus the Lock Screen ignores any Auto-Brightness setting making it shine more brightly than if you were to proceed to the Home Screen.
[crarko adds: I tested this, and it works as described. It's good if you need the lighting briefly. The obvious reason for the flashlight apps is that sometimes one needs the light for more than a minute. And sometimes they operate as tethering proxies. (That's a joke, folks.)]
As is well-known for iOS devices, if you press and hold the Home button and then immediately press the Sleep/Wake button, a screenshot of the current screen will be taken. The screenshot is saved to the 'Saved photos' album in the Photo app.
What may not be obvious is that this even works when playing a video; the current frame is saved without interrupting the videostream. This works for videos playing in the iTunes app and also in the YouTube app, so it appears to be available globally.
[crarko adds: I tested this on my iPhone, and it works as described. The author used it with an iPad.]
While the iTunes Remote for iPhone app from Apple is very cool many of us are still waiting for a script editor to make it's appearance on iOS. This AppleScript will allow you to run specific pre-written scripts on your Mac from your iPhone, using iTunes as an intermediary.
This is a simple bash script I made that will prevent iTunes from updating any device. To update after you use this script you just manually download the firmware and do option restore. I made it because I was hearing about a lot of people who 'accidentally' upgraded to a non-jailbreakable firmware.
The release of iOS 4.1 fixed many Bluetooth connection problems from iOS 4.0. However it introduced a significant problem with volume over Bluetooth. Any audio from the iPhone over Bluetooth is very low, to the point of being inaudible, even with volume turned to max on the Bluetooth device and the Bluetooth volume on maximum on the iPhone.
After much discussion over many threads at the Apple support boards, a number of 'fixes' were found but most of them resulted in temporary resolution. These includes resetting iPhone settings and/or deleting the Bluetooth device from the iPhone and re-adding it. This thread discusses the actual fix, and I have pasted the contents below.
I have used this hint when setup up my iPhones in the past as I hate excess icons on my SpringBoard. That hint doesn't seem to work any more under iOS4.x.
To be sure the addition of Folders in iOS4.x has helped reduce clutter, but I never use
Compass, Stocks, or Voice Memos and other apps that need to be present on the SpringBoard for their other functions to operate (e.g. Tomtom Carkit tool).
I stumbled across this method while editing plists trying to make a 5 icon Dock on my non-jailbroken 4.0 iPhone 3GS.
Note that this hint requires connecting your iPhone to a Windows machine, either directly or through a virtualization application such as Fusion or Parallels.
In older versions of the iPhone OS software, it was possible to enter Field Test mode to get a lot of useful data about the cellular connection. This capability was removed in iOS 4.0, and caused some angst while trying to examine the iPhone 4 antenna reception issues.
The ability has been restored, although to a greatly limited degree, with iOS 4.1. Once again, if you dial the number *3001#12345#* in the keypad you will enter FTM. What you will see now is a negative number (presumably representing the signal loss in dB) in the upper left that replaces the cellular signal strength bars. A more negative number means lower relative signal strength, so the -121 I have at the moment is worse than the -92 I had in a different room in the house. Zero would be no signal loss.
To exit Field Test mode, just press the Home button. It may take a moment for the number to go away and be replaced by the bars again.
I think we all hope that when iOS 4.2 is released (Apple says in November) it will restore full Field Test mode with all the diagnostic data available, and maybe bring it to the 3G enabled iPad as well.