ios options to create time-based reminders or messages

[Richard Miller]

What are the options to implement a reminder system in an ios/LC app 
which will alert the user periodically on their ios device, even though 
the app is not running in the foreground?

For example, the user runs the app and sets it to remind them twice 
daily to do a specific task. How can this reminder be implemented?

Some ideas:

- push notification (is this fairly easy to implement?)
- having an external server send SMS messages to the user's device on 
the specified time interval
- something similar to the way various ios Alarm clock apps work... but 
I don't know if this can be implemented through LC.

Thanks.
Richard Miller