What the best way to store messages with image locally

Hi everyone,

I'm developping an iOS applicaiton which user can have private chat with other users.

Actually when a user received a message I create a new "Message" object which containt: FromId, ToId, Message, Image, date

I add the message to my existing array of message like this MyExistingMessage.add(Message)

Finally I save the array on the iPhone memory using UserDefault with the uniqueId of the other user.

Here a representation of what i have on the memory of the iPhone after multiple discutions.

DiscutionXinMemory[[Message], [Message], [Message]]

DiscutionYinMemory[[Message], [Message], [Message]]

This solution is not optimized because it's take time to load the message and if I save too much image it's may crash the application.

So I have think to create a local database to save my message but I want an external review before rewriting this part of my code.

Is a local database appropriate to save text and image ?

I hope you will understand me (English is not my mother tongue)

Thank you