Barcode Studio is the free barcode generating solution for iOS.
Currently the app is able to encode data in over 40 barcode symbologies.
Encoding happens on the smartphone and not with the help of a webservice. Therefor you can create barcodes without being connected to the internet.
The app is licenced under the terms of the GNU General Public License.
The 13th digit of a EAN13 is a check digit which is automatically calculated by the app. If you enter the first 12 digits, the resulting barcode will contain 13 digits.