This wikiHow teaches you how to automatically add Jewish holidays within the iPhone's "Calendars" application. Religious events and holidays will appear next to other personal events and important holidays, and the current Jewish date will be shown next to the iPhone clock.
Steps
Step 1. Open the iPhone settings
The icon looks like a gray gear and is located on one of the main screens.
If you don't see it on one of the main screens, it might be inside the "Utilities" folder
Step 2. Scroll down and tap Calendars
It is located in the fifth group of menu options.
Step 3. Tap Alternate Calendars
It is located in the second group of menu options.
Step 4. Tap Hebrew
A check mark will appear next to this item. Holidays and other Jewish events will appear in the "Calendars" application. Also, on the lock screen you will see the current date according to the Hebrew calendar, entered under the iPhone clock and the Gregorian date.