Realm is a mobile database: a replacement for Core Data & SQLite

  https://realm.io

Realm is a mobile database that runs directly inside phones, tablets or wearables. This repository holds the source code for the iOS, macOS, tvOS & watchOS versions of Realm Swift & Realm Objective-C.

Features

• Mobile-first: Realm is the first database built from the ground up to run directly inside phones, tablets and wearables.
• Simple: Data is directly exposed as objects and queryable by code, removing the need for ORM's riddled with performance & maintenance issues. Most of our users pick it up intuitively, getting simple apps up & running in minutes.
• Modern: Realm supports relationships, generics, vectorization and even Swift.
• Fast: Realm is faster than even raw SQLite on common operations, while maintaining an extremely rich feature set.

Getting Started

Please see the detailed instructions in our docs to add Realm Objective-C or Realm Swift to your Xcode project.

Documentation

Realm Objective-C

The documentation can be found at realm.io/docs/objc/latest.
The API reference is located at realm.io/docs/objc/latest/api.

Realm Swift

The documentation can be found at realm.io/docs/swift/latest.
The API reference is located at realm.io/docs/swift/latest/api.

Getting Help

• Need help with your code?: Look for previous questions on the #realm tag — or ask a new question. We actively monitor & answer questions on SO!
• Have a bug to report? Open an issue. If possible, include the version of Realm, a full log, the Realm file, and a project that shows the issue.
• Have a feature request? Open an issue. Tell us what the feature should do, and why you want the feature.
• Sign up for our Community Newsletter to get regular tips, learn about other use-cases and get alerted of blogposts and tutorials about Realm.

Building Realm

In case you don't want to use the precompiled version, you can build Realm yourself from source.
Prerequisites:

• Building Realm requires Xcode 8.x.
• If cloning from git, submodules are required: git submodule update --init --recursive.
• Building Realm documentation requires jazzy

Once you have all the necessary prerequisites, building Realm.framework just takes a single command: sh build.sh build. You'll need an internet connection the first time you build Realm to download the core binary.
Run sh build.sh help to see all the actions you can perform (build ios/osx, generate docs, test, etc.)

from  https://github.com/realm/realm-cocoa