1. XML-based (the entire database is one xml file)
2. SQLite-based
3. Roll your own (by providing an implemention)
#1 is terribly slow for most cases and not publicly available on iOS.
#3 was released early in the ioS lifecycle (iOS 3 or iOS 5, depending which piece we're talking about)
SQL is, for most purposes, the only implementation, except for iTunes which used #1 for a decade after #2 clearly won.
1. XML-based (the entire database is one xml file)
2. SQLite-based
3. Roll your own (by providing an implemention)
#1 is terribly slow for most cases and not publicly available on iOS.
#3 was released early in the ioS lifecycle (iOS 3 or iOS 5, depending which piece we're talking about)
SQL is, for most purposes, the only implementation, except for iTunes which used #1 for a decade after #2 clearly won.