The best replacement for core data is sqlite.

The best alternatives to core data are rated as following:
★★★★★  sqlite
★★★  fmdb
★★★  sqlite ios
★★  plist
★★  nsuserdefaults
★★  sqlite iphone
★★  nscoding
★  archiving
★  user defaults
★  sqlite3
  nskeyedarchiver

Your alternative for core data is not listed? Suggest!
Speaking about core data, one probably shouldn't forget about sqlite.

Other search terms related to core data and their ratings are:
★★★★★ sqlite
★★★ parse
★★★ existing sqlite database
★★ table view
fetchedresultscontroller
arc
You have in mind a companion for core data and it is not yet here? Propose!



Google Trends

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core data
sqlite
fmdb