CombineRealm

Combine is a lightweight framework that is written is pure Swift. It allows to seamlessly use Apple Combine Framework with Realm.

Installation

CombineRealm is avaialble via Carthage or Swift Package Manager.

Requirements

iOS 13.0+
Swift 5+
Realm 3.21.0+
Carthage 0.18+ (if you use)

Carthage

To install CombineRealm with Carthage, add the following line to your Cartfile.

github "yaroslav-zhurakovskiy/CombineRealm"

Swift Package Manager

You can use The Swift Package Manager to install CombineRealm by adding the proper description to your Package.swift file:

// swift-tools-version:5.1
import PackageDescription

let package = Package(
	name: "YOUR_PROJECT_NAME",
	dependencies: [
		.package(url: "https://github.com/yaroslav-zhurakovskiy/CombineRealm.git", from: "1.2.1"),
	]
)

Usage

Observing changes

Some "Message" type that will be used in the examples

class Message: Object {
    @objc dynamic var id: String = UUID().uuidString
    @objc dynamic var body: String = ""
    
    convenience init(_ text: String) {
        self.init()

        body = text
    }
}

Observe objects

let realm = try Realm()
let infoLabel = UILabel()
var cancelSet = Set<AnyCancellable>()

realm.objectsPublisher(Message.self)
	.map { list in "You have \(list.count) messages!" }
	.catch { error in Just("Realm error: \(error.localizedDescription)") }
	.assign(to: \.text, on: infoLabel)
	.store(in: &cancelSet)

Observe collection changes

let realm = try Realm()
let infoLabel = UILabel()
var cancelSet = Set<AnyCancellable>()

realm.objects(Message.self).observeChangePublisher()
	.map { changes in
		switch changes {
		case .initial(let messages):
			return "Initial \(messages.count)"
		case let .update(messages, deletions, insertions, modifications):
			var text =  "Update \(messages.count)."
			text += "\nDeletions: \(deletions)"
			text += "\nInsertions: \(insertions)"
			text += "\nModifications: \(modifications)"
			return text
		case .error(let error):
			return "Realm error: \(error.localizedDescription)"
		}
	}
	.assign(to: \.text, on: infoLabel)
	.store(in: &cancelSet)
}

Observe changes in an object

class UserSettings: Object {
	@objc dynamic var email: String = ""
	@objc dynamic var company: String = ""
}

let userSettings = UserSettings()
let infoLabel = UILabel()
var cancelSet = Set<AnyCancellable>()

userSettings.observePublisher()
	.map { change in
		switch change {
		case .change(let properties):
			let settings = properties.map { $0.name }.joined(separator: "")
			return "User changed settings: \(settings)"
		case .deleted:
			return "User deleted the settings."
		}
	}
	.catch { error in Just("Realm error: \(error.localizedDescription)") }
	.assign(to: \.text, on: infoLabel)
	.store(in: &cancelSet)

Writing changes

let realm = try Realm()
let currentMessage = Message("Some message to edit...")
try realm.write {
	realm.add(currentMessage)
}
let editMessageField =  UITextField()
var cancellableSet = Set<AnyCancellable>()

editMessageField.publisher(for: \.text)
	.map { $0 ?? "" }
	.write(to: realm) { _, newMessageText in
		currentMessage.body = newMessageText
	}
	.store(in: &cancellableSet)

Adding objects

let realm = try Realm()
var cancelSet = Set<AnyCancellable>()
let messageField =  UITextField()
let sendButton = UIButton()

sendButton.publisher(for: .touchUpInside) 
	.compactMap { messageField.text }
	.filter { text in !text.isEmpty }
	.map { text in Message(text) }
	.add(to: realm)
	.store(in: &cancelSet)

Just(Message("I am great!"))
	.add(to: realm)
	.store(in: &cancelSet)

Deleting objects

let realm = try Realm()
var cancelSet = Set<AnyCancellable>()

Publishers.Sequence(sequence: ["message-id#1", "message-id#2"])
	.compactMap { messageID in
		return realm.object(ofType: Message.self, forPrimaryKey: messageID)
	}
	.delete(from: realm)
	.store(in: &cancelSet)

Note

Instead of sugar syntax you can always use the coresponding types:

// Publishers
ObserveChangePublisher
ObserveElementsPublisher
ObserveObjectPublisher

// Subscribers
Realm.Add
Realm.Write
Realm.TryWrite
Realm.Delete