Tetra

A description of this package. This provides some features that were only available at least iOS 15 and macOS 12.

iOS 15, macOS 12 등에서만 사용이 가능한 API를 iOS 13, iOS 10.15 등에서 사용할 수 있도록 하는 것으로 목표로 개발되었습니다.

Backport

async await URLSession download, upload

async await NSManagedContext peform

Combine <-> AsyncSequence interchanging

CompatAsyncPublisher

CompatAsyncThrowingPublisher

MapTask

TryMapTask

MultiMapTask

SwiftUI.AsyncImage SwiftUI.Binding Collction conformance SwiftUI.List Pull to Refresh

Usage

(Try)MapTask

Transform upstream value using async (throwing) closure in Serial manner. Only one transformer runs at a time. Wil be migrated to MultiMapTask.

import Combine
import Tetra
        
        let cancellable = (0..<20).publisher
            .tryMapTask { _ in
                // Underlying Task is cancelled if subscription is cancelled before task completes.
                try await URLSession.shared.data(from: URL(string: "https://google.com")!)
            }.map(\.0).sink { completion in
                
            } receiveValue: { data in
                
            }

MultiMapTask

!Experimantal

Transform upstream value using async closure in Concurrent manner. Transformer runs up to maxTasks in concurrent manner managed by TaskGroup. maxTasks = 1 has same behavior with (Try)MapTask.

import Combine
@_spi(Experimental) import Tetra
        
        let cancellable = (0..<20).publisher
            .setFailureType(to: URLError.self)
            .multiMapTask(maxTasks: .unlimited) { _ in
                // Underlying Task is cancelled if subscription is cancelled before task completes.
                do {
                    let (data, response) = try await URLSession.shared.data(from: URL(string: "https://google.com")!)
                    return .success(data) as Result<Data,URLError>
                } catch {
                    return .failure(error as! URLError) as Result<Data,URLError>
                }
            }.sink { completion in
                
            } receiveValue: { data in
                
            }

AsyncSequencePublisher

Transform AsyncSequence to Publisher

import Combine
import Tetra
        
        let cancellable = AsyncStream<Int> { continuation in
            continuation.yield(0)
            continuation.yield(1)
            continuation.finish()
            // Underlying AsyncIterator and Task receive task cancellation if subscription is cancelled.
        }.tetra.publisher
            .catch{ _ in Empty().setFailureType(to: Never.self) }
            .sink { number in
                
            }

[NotificationSequence]

AsyncSequence compatible with `NotificationCenter.Notifications` Available even in iOS 13

import Combine
import Tetra
import UIKit
        
        // use NotificationCenter.Notifications if available otherwise use NotficationSequence under the hood
        for await notification in NotificationCenter.default.tetra.notifications(named: UIApplication.didFinishLaunchingNotification) {
            
        }

CompatAsync(Throwing)Publisher

AsyncSequence compatible with `Async(Throwing)Publisher` Available even in iOS 13

import Combine
import Tetra
        
        let publisher = URLSession.shared.dataTaskPublisher(for: URL(string: "https://google.com")!)
        // use AsyncThrowingPublisher if available otherwise use CompatAsyncThrowingPublisher under the hood.
        for try await (data, response) in publisher.tetra.values {
            
        }

RefreshableScrollView

Compatible pull to refresh feature in all version for iOS

import SwiftUI
import Tetra
        
struct ContentView: View {
    
    var body: some View {
        RefreshableScrollView {
            
        }
        .refreshControl {
            await fetchData()
        }
    }
}

Known Issues

MapTask and TryMapTask, MultiMapTask could lose the value when using with PublishSubject or CurrentValueSubject.

• This is because, Swift does not allow running task inline(run task until reaching suspending point). So MapTask operators need additional time to for warmup.

• To fix this issue, use MapTask family inside the FlatMap or attach buffer before them.

TODO

• Add more Tests

• Swift 6 Concurrency model

• FullTypedThrow for powerful generic failure

• more fine grained way to introduce extension methods (maybe something like .af in Alamofire?)

• remove all AsyncTypedSequence and WrappedAsyncSequence dummy protocol when FullTypedThrow is implemented.