Set a Passcode Lock On iPhone 4

Apple's iOS includes a feature that lets you block access to your iPhone until a password -- either numeric or alphanumeric -- is entered on the device.

Follow these simple steps to set-up Passcode Lock:

1. Go into Settings.
2. Open General.
3. Scroll down and tap on Passcode Lock.
   1. The default passcode in iOS is four digits -- if you would like to set an alphanumeric passcode, slide the Simple Passcode toggle to Off
4. Now, select Turn Passcode On.
5. Enter a four-digit passcode, or an alphanumeric passcode of any length.
6. Re-type your passcode to confirm.
7. Set Require Passcode to the desired time -- this will be the amount of idle time before your iPhone will require you to enter the passcode. 

It's so simple!