Base64CoderSwiftUI

This is a simple base64 coder with dynamic updates.

Urgent

This project is powered by Combine framework and suggested task can be accomplished by merging two publishers.

class PublishersModel: BindableObject {
    @Published var raw: Raw
    @Published var pretty: Pretty
    
    var didChange: AnyPublisher<Result<(Raw, Pretty), Error>, Never> = Publishers.Empty().eraseToAnyPublisher()
    required init(raw: Raw, pretty: Pretty) {
        self.raw = raw
        self.pretty = pretty
        
        let rawPublisher = $raw.map { (raw) -> Result<(Raw, Pretty), Error> in
            let decoded = Base64Coder.decode(value: raw.string).flatMap { JSON64Coder.decode(value: $0) }
            return decoded.flatMap { rhs in
                return .success((Raw(string: raw.string), Pretty(string: rhs)))
            }
        }
        
        let prettyPublisher = $pretty.map { (pretty) -> Result<(Raw, Pretty), Error> in
            let encoded = JSON64Coder.encode(value: pretty.string).flatMap { Base64Coder.encode(value: $0) }
            return encoded.flatMap { lhs in
                return .success((Raw(string: lhs), Pretty(string: pretty.string)))
            }
        }
                
        let publisher = rawPublisher.merge(with: prettyPublisher).eraseToAnyPublisher()
        self.didChange = publisher
    }
}

Purpose

This project shows corner stones of mutually connected components with single source of truth in SwiftUI.

Overview

We have a model which provides two bindings: raw and pretty for EncodedView and DecodedView respectively.

On each update we receive didSet hook in model where we should check if value of mutual connected component is changed.

Also we have an error indication which is hosted at ErrorView.

Data Workflow

EncodedView

1. Receive update.
2. Call didSet.
3. Check error absence.
4. Check pretty similarity.
5. Call didChange.

DecodedView

1. Receive update.
2. Call didSet.
3. Check error absence.
4. Check raw similarity.
5. Call didChange.