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.
Apple made it quite easy and intuitive to quit out of apps in iOS 4; however I have not seen this method mentioned anywhere.
Double tap the Home button to bring up the multitasking applications view, then tap and hold on an app (as if you were arranging your home screen). A small red circle will appear on each app; tap one to close that app. And, of course, you can still swipe through the list to see more.
[crarko adds: I can't test this one on my iPhone 3G. Please confirm that this works.]
These are not my creation, but I've found the tips in this webpage very useful for mastering iPad (and iPhone) typing. Full credit goes to that site.
There is a list of ten useful tips for making efficient use of the onscreen keyboard(s) in iOS based devices. Some of them are generally known, such as the URL autocomplete and spellchecking completion, but others are less widely publicized, such as the final tip about toggling the alpha and numeric keyboards.
[crarko adds: I tested some of these on my iPhone, and they worked as described. There are some screen captures and a video on the referenced web site which shows how these tips appear. I'm putting this up because keyboard shortcut hints are generally useful things, but I refer you directly to the original site to preserve their copyright.]
I've been noticing for weeks now that several of my repeating appointments are showing up at the wrong time on my iPhone's Calendar application, even though the right time shows up in iCal on my desktop. The appointments are showing up on the right day, but many hours earlier, e.g. 4:00 AM.
In iCal on my Mac, I opened one of the events that was showing up incorrectly on my phone. Lo and behold, the 'Time Zone' setting was set to floating, rather than to my local zone (North America Central Time). Apparently this was true of all my repeating events that had been around for a long time, presumably before I upgraded to Leopard or Snow Leopard and iCal included time zone support. Just set the time zone to the appropriate region, make sure to change this for all future events, and all should be well.
[crarko adds: I looked in iCal on my machine and all the time zone information appeared to be correct, so this may, as implied, be the residual result of multiple upgrades to iCal.]