IceCream: A Swift repository from Capevace

IceCream helps you sync Realm Database with CloudKit.

It works like magic!

Features

Prerequisite

Be sure to have enrolled in Apple Developer Program
Turn on your iCloud in Capabilities and choose CloudKit
Turn on Background Modes and check Background fetch and Remote notification

Usage

Basics

Prepare your Realm Objects (e.g. Dog, Cat...):

class Dog: Object {
    @objc dynamic var id = NSUUID().uuidString
    @objc dynamic var name = ""
    @objc dynamic var age = 0
    @objc dynamic var isDeleted = false

    static let AVATAR_KEY = "avatar"
    @objc dynamic var avatar: CreamAsset?

    @objc dynamic var owner: Person? // to-one relationships must be optional

    override class func primaryKey() -> String? {
        return "id"
    }
}

Do stuff like this:

extension Dog: CKRecordConvertible {
    // Leave it blank if you are using private database
    // For public database users, uncomment the following code:
    // static var databaseScope: CKDatabase.Scope {
    //     return .public
    // } 
}

extension Dog: CKRecordRecoverable {
    // Leave it blank
}

Is that easy? Protocol Extensions do this trick.

Start the Engine!

var syncEngine: SyncEngine?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    ...
    syncEngine = SyncEngine(objects: [
            SyncObject<Person>(),
            SyncObject<Dog>(),
            SyncObject<Cat>()
        ], databaseScope: .private)
    application.registerForRemoteNotifications()
    ...
}

Listen for remote notifications

The sample code in AppDelegate will be a good reference.

That's all you need to do! Every time you write to Realm, the SyncEngine will get notified and handle sync stuff!

For more details, clone the project to see the source code.

Object Deletions

Yep, we highly recommend you use Soft Deletions. That's why we add an isDeleted property to CKRecordConvertible protocol.

When you want to delete an object, you just need to set its isDeleted property to true and the rest of the things are already taken care of.

You also don't need to worry about cleaning-up things. It has also been considered.

How about syncing asset?

Luckily, we have a perfect solution for syncing asset. Absolutely, you could also store your image or kind of resource stuff as Data type and everything works fine. But Realm has a 16MB limit of data property. And CloudKit encourages us to use CKAsset in places where the data you want to assign to a field is more than a few kilobytes in size. So taking the consideration of the above two, we recommend you to use CreamAsset property to hold data. CreamAsset will store local data on the file system and just save file paths in the Realm, all automatically. And we'll wrap things up to upload to CloudKit as CKAsset.

An example project is provided to see the detailed usage.

Relationships

Thanks to the CKReference in the CloudKit, IceCream has supported many-to-one relationship nicely. As the Dog example shows, a dog may have an owner. And we'll wrap the owner up as CKReference and push them to the CloudKit.

Inversely, the Person object has a dogs property which is the type of LinkingObjects. So we've successfully supported to-many relationship with a nice workaround. All make sense.

Requirements

iOS 10.0+ / macOS 10.12+ / tvOS 10.0+ / watchOS 3.0+
Swift 5

Debug Suggestions

It's true that debugging CloudKit is hard and tedious. But I have some tips for you guys when facing puzzles:

You should know how Realm and CloudKit works.
Using GUI tools, like Realm Browser and CloudKit Dashboard.
When you are lost and don't remember where you are, I suggest starting all over again. In CloudKit Dashboard, "Reset..." button is provided. You can also clear local database by re-install apps.
By default, IceCream only prints some logs to your console in DEBUG mode. However, you could turn it off by adding IceCream.shared.enableLogging = false if it bothers you.
Keep calm and carry on!

Warning: If you're going to launch your app onto App Store, don't forget to deploy your environment settings to production. You can do it easily in the CloudKit Dashboard. Write & Read permissions are also need to be considered.

One More Tip

How to debug CloudKit in production mode? See this post.

Example

To run the example project, clone the repo, and run pod install from the Example directory first.

Installation

Using Carthage or CocoaPods.

Carthage

Carthage is a decentralized dependency manager for Cocoa applications.

To integrate IceCream into your Xcode project using Carthage, specify it in your Cartfile:

github "caiyue1993/IceCream"

Then, run the following command to build the frameworks:

carthage update

Normally, you'll get IceCream, Realm and RealmSwift frameworks. You need to set up your Xcode project manually to add these 3 frameworks.

On your application targets’ General settings tab, in the Linked Frameworks and Libraries section, drag and drop each framework to use from the Carthage/Build folder on disk.

On your application targets’ Build Phases settings tab, click the “+” icon and choose “New Run Script Phase”. Create a Run Script with the following content:

/usr/local/bin/carthage copy-frameworks

and add the paths to the frameworks you want to use under “Input Files”(taking iOS platform for example):

$(SRCROOT)/Carthage/Build/iOS/IceCream.framework
$(SRCROOT)/Carthage/Build/iOS/Realm.framework
$(SRCROOT)/Carthage/Build/iOS/RealmSwift.framework

For more information about how to use Carthage, please see its project page.

CocoaPods

IceCream is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod 'IceCream'

If you want to build IceCream as a static framework, CocoaPods 1.4.0+ is required.

Make it better

This is the to-do list for the IceCream project. You can join us to become a contributor.

CloudKit Shared Database

See the CONTRIBUTING file for contributing guidelines.

Live Demo

My app Sprint (A lightweight task management app) is using IceCream. You can download it and try it on your multiple devices to see this magic.

Reference

Synchronizing data with CloudKit (Recommended)
CloudKit Best Practices
Mastering Realm Notifications

Backers

By now, IceCream is mainly maintained by myself. I'd be appreciated if you could be a backer to support the maintenance of IceCream. Thank you to all our backers! Become a backer

Contributors

This project exists thanks to all the people who contribute. Contribute.

Donations

Now IceCream has been adopted by hundreds of developers and successfully used in their apps. We're greatly humbled by your enthusiam around the projects, and want to continue to move this project forward. Your financial support will encourge me to spend more time and provide better services.

Any amount you can donate today to help us reach our goal would be greatly appreciated.

License

IceCream is available under the MIT license. See the LICENSE file for more info.

Capevace/IceCream