Mac App to show logs

MacApp.swift

//
//  LogFetcher.swift
//  LogQuery
//
//  Created by Kraig Spear on 5/13/18.
//  Copyright © 2018 spearware. All rights reserved.
//

import Foundation
import SpearSwiftLibmacOS

protocol LogFetchable {
    func fetch(completed: @escaping (LogResult) -> Void)
}

typealias LogResult = NetworkResult<[Log]>

struct LogRequest {}

enum LogFetchError: Error {
    case failedToParse
}

extension LogRequest: RequestBuildable {
    var request: URLRequest {
        var url = URL(string: "")!
        url = url.add(code: "", max: "100")

        var request = URLRequest(url: url)

        request.httpMethod = "GET"

        return request
    }
}

final class LogFetcher: LogFetchable {
    func fetch(completed: @escaping (LogResult) -> Void) {
        let logRequest = LogRequest()
        let sessionConfig = URLSessionConfiguration.default
        let session = URLSession(configuration: sessionConfig)

        let task = session.dataTask(with: logRequest.request) { data, response, error in
            if let error = error {
                print(error)

                DispatchQueue.main.async {
                    completed(NetworkResult.error(error: error))
                }

                return
            }

            let statusCode = (response as! HTTPURLResponse).statusCode

            if statusCode != 200 {
                DispatchQueue.main.async {
                    completed(LogResult.response(code: statusCode))
                }
                return
            }

            if let data = data {
                do {
                    let logs = try JSONDecoder().decode([Log].self, from: data)
                    DispatchQueue.main.async {
                        completed(LogResult.success(result: logs))
                    }
                } catch let error {
                    DispatchQueue.main.async {
                        completed(LogResult.error(error: error))
                    }
                }

            } else {
                preconditionFailure("Invalid state, not code, error or data")
            }
        }

        task.resume()
        session.finishTasksAndInvalidate()
    }
}

private extension URL {
    func add(code: String, max: String) -> URL {
        var params: NetworkParameterType = NetworkParameters()
        params = params.addParam("code", value: code)
        let url = params.NSURLByAppendingQueryParameters(self)
        return url
    }
}


// ViewModel

//
//  MainViewModel.swift
//  LogQuery
//
//  Created by Kraig Spear on 5/13/18.
//  Copyright © 2018 spearware. All rights reserved.
//

import Foundation
import SpearSwiftLibmacOS

final class MainViewModel {
    private let logFetcher: LogFetchable
    
    init(logFetchable: LogFetchable) {
        self.logFetcher = logFetchable
    }
    
    convenience init() {
        self.init(logFetchable: LogFetcher())
    }
    
    private let logsObservable = Observable<[Log]>(value: [])
    private let busyObservable = Observable<Bool>(value: false)
    
    var logs: AnySubscribeable<[Log]> {
        return logsObservable.asSubscribeable
    }
    
    var isBusy: AnySubscribeable<Bool> {
        return busyObservable.asSubscribeable
    }
    
    func reload() {
        busyObservable.value = true
        logFetcher.fetch { [weak self] result in
            guard let mySelf = self else { return }
            
            switch result {
            case let .success(result: logs):
                mySelf.logsObservable.value = logs
            default:
                break
            }
            
            mySelf.busyObservable.value = false
        }
    }
}

1. Code to fetch logs
2. ViewModel that calls

Note

The observable is not Rx, but my own simple class that allows multiple listeners on a property (similar to Rx without the baggage and complexity) A standard delegate pattern would work fine.