In order to display ipad screen on computer monitor or tv you can buy the small accessory which mirror ipad display on your tv or projector using the HDMI cable, the same accessory can be used to display the screen on your ipod touch or iphone to your tv, by default this accessory does not support ipod or iphone as shown in the image below.
In order to do this with your iphone, ipod or ipad 1 touch you will need to have your device jailbroken, if your device needs to be already jailbroken on iOS 4.3.1 or later in case you have iPad 2nd generation, it has a built-in ability to mirror the display on your TV or monitors using Apple display adapter.
Screen Display Mirror iPad 1G, iPhone 4, iPod touch 4G Display on HDTV, Monitor, or Projector
1. Install OpenSSH from cydia and then enable SSH on your iphone, make sure that both your computer and iphone are connected to the same wifi network.
2. Connect your iphone using free Filezilla and enter the Wi Fi IP address of your device, to find this address your apple device go to "Settings" >> "WiFi", and then click the blue arrow next to wireless network.
and use root and username and alpine as password, which is the default password and 22 as port number as iphone supports SFTP as shown in the image below.
and go to the following path
3. Find and download this file on your computer:
- For iPad 1st Generation, download "K48AP.plist" file
- For iPhone 4, download "N90AP.plist" file
- For iPod touch 4th Generation, download "N81AP.plist" file
4. After you have downloaded the file, open it using "TextWrangler" if you are on Mac, or use "Plist Editor" if you are on Windows and Add the following line of code just before <key>displayport</key> as shown in the image below.
5. Once you added the additional code to the file, Save the file and then upload it back to your device using SSH to the same location overwriting the existing file.
6. Restart your apple device and try connecting your ipod, iphone or old ipad 1 using the ipad 2 display adaptor, you will see the display mirrored on your monitor as shown in the image below.
As you can see in the image above.