Combine Extensions

What is Combine Extensions?

Requirements

• Xcode 14.2+
• Swift 5.7+

Installation

The easiest way to install CombineExtensions is by adding a dependency via SPM.

        .package(
            name: "CombineExtensions",
            url: "https://github.com/krogerco/combineextensions-ios.git",
            .upToNextMajor(from: Version(1, 0, 0))
        )

…then reference in your test target.

        .testTarget(
            name: "MyTests",
            dependencies: [
                .byName(name: "MyFramework")
                .product(name: "CombineExtensions", package: "CombineExtensions-iOS")
            ],
            path: "MyFrameworkTests"
        )

How to Use Combine Extensions

Sink to Function Reference

Prevent retain cycles by sinking to a function reference on a weakly retained object.

// Good
publisher
    .sink(to: CartViewModel.handleEvent, on: self, ownership: .weak) // Safely captured!
    .store(in: &subscriptions)
    
// Bad
publisher
    .sink(receiveValue: self.handleEvent) // `self` captured in subscription, causing retain cycle.
    .store(in: &subscriptions)

Weakly Assign

The default Combine assign(to:on:) function strongly retains the object. We have provided an overload to allow retaining that object weakly.

publisher
    .assign(to: \.textfield.text, on: self, ownership: .weak)
    .store(in: &subscriptions)

Subscribe to Multiple Notification.Names

Use NotificationCenter.publisher(for names:) to subscribe to multiple notifications and funnel them into a single stream.

NotificationCenter.default.publisher(for: [Notification.Name.CartUpdate, Notification.Name.RefreshAll])
    .sink { notification in 
        // Notifications from either source are funneled into a single event.
        switch notification.name {
            case Notification.Name.CartUpdate: //
            case Notification.Name.RefreshAll: //
        }
    }
    .store(in: &subscriptions)

withLatestFrom Operator

Merges two publishers into a single publisher by combining each value from self with the latest value from the other publisher, if any.

let buttonTap = PassthroughSubject<Void, Never>()
let formData = CurrentValueSubject<FormData, Never>()

let publisher = buttonTap
    .withLatestFrom(formData)
    .sink { _, formData in 
        //
    }
}

buttonTap.send()
formData.send(formData.updated()) // Won't trigger publisher, waiting on buttonTap to send again.
formData.send(formData.updated())
formData.send(formData.updated())
buttonTap.send()

Documentation

CombineExtensions has full DocC documentation. After adding to your project, Build Documentation to add to your documentation viewer.

Online Documentation

Full Documentation

Communication

If you have issues or suggestions, please open an issue on GitHub.