The last part of this trio of tutorials for creating an iPhone graphic will show you how to export the vector character and save it for the different screen resolutions of the iOS devices.
Open Photoshop and create a new document. Go back to Illustrator and select your artwork making sure that you do not select the original drawing on the bottom layer. Now got to Edit > Copy (Cmd + C / Ctrl + C), switch back to Photoshop and select Edit > Paste (Cmd + V / Ctrl + V). Photoshop will ask how you would like to import the artwork. Choose Smart Object, click OK and then press Enter to place the artwork.