Before You Begin
If you use iPhone, iPod touch, or iPad to access sensitive data, such as your email or calendar, you should consider setting a passcode lock. Doing so protects your data in case an untrustworthy person gets a hold of your device (for example, if it is lost or stolen).
Set a Passcode Lock on iPhone, iPod touch, and iPad
To set a passcode lock for iPhone, iPod touch, and iPad do the following:
Press Settings > Passcode Lock.
Enter a 4-digit code that will serve as your passcode.
Enter your passcode again.
Your device now requires your passcode to unlock it. You must enter your passcode when you turn on the device or press the Wake button.
On iPhone, you do not have to enter your passcode to answer calls or make emergency calls. You must enter your passcode to make normal calls.
Advanced Options
By default, if you have a passcode set for iPhone, iPod touch, and iPad, you must enter it immediately after turning on the device or pressing the Wake button.
You can change the length of time your device is idle before your passcode is required. For example, you can set the device to only require a passcode after it has been idle for more than five minutes.
To change the length of time before your passcode is required, do the following:
Press Settings > Passcode Lock > Require Passcode.
Select a length of time. Shorter times are more secure.