JohnSundell

extension Dictionary {
    mutating func value(for key: Key, orAdd closure: @autoclosure () -> Value) -> Value {
        if let value = self[key] {
            return value
        }
        
        let value = closure()
        self[key] = value
        return value
    }

JohnSundell

class Cache<T> {
    private lazy var objects = [String : T]()
    
    func object(forKey key: String) -> T? {
        return objects[key]
    }
    
    func addObject(_ object: T, forKey key: String) {
        objects[key] = object
    }

JohnSundell

import UIKit

// Create a protocol that defines what APIs that you need from the singleton
protocol Application {
    func open(url: URL)
}

// Make the singleton-based class conform to your protocol
extension UIApplication: Application {
    func open(url: URL) {

JohnSundell

/**
 *  Perform a throwing expression, and throw a custom error in case the expression threw
 *
 *  - parameter expression: The expression to execute
 *  - parameter error: The custom error to throw instead of the expression's error
 *  - throws: The given error
 *  - returns: The return value of the given expression
 */
func perform<T>(_ expression: @autoclosure () throws -> T, orThrow errorExpression: @autoclosure () -> Error) throws -> T {
    do {

JohnSundell

/**
 *  Copyright (c) John Sundell 2017
 *  Licensed under the MIT license
 */

import Foundation
import XCTest

/**
 *  Assert that an expression throws a given error

JohnSundell

import UIKit

class OnboardingManager {
    private let userDefaults: UserDefaults

    init(userDefaults: UserDefaults = .standard) {
        self.userDefaults = userDefaults
    }

    func presentOnboardingControllerIfNeeded(in viewController: UIViewController) {

JohnSundell

func loadSearchData(matching query: String) throws -> Data {
    let urlString = "https://my.api.com/search?q=\(query)"
    
    guard let url = URL(string: urlString) else {
        throw SearchError.invalidQuery(query)
    }
    
    return try Data(contentsOf: url)
}

JohnSundell

func loadSearchData(matching query: String) throws -> Data {
    let urlString = "https://my.api.com/search?q=\(query)"
    
    guard let url = URL(string: urlString) else {
        throw SearchError.invalidQuery(query)
    }
    
    do {
        return try Data(contentsOf: url)
    } catch {

JohnSundell

func perform<T>(_ expression: @autoclosure () throws -> T,
                orThrow error: Error) throws -> T {
    do {
        return try expression()
    } catch {
        throw error
    }
}

JohnSundell

func loadSearchData(matching query: String) throws -> Data {
    let urlString = "https://my.api.com/search?q=\(query)"
    
    guard let url = URL(string: urlString) else {
        throw SearchError.invalidQuery(query)
    }
    
    return try perform(Data(contentsOf: url),
                       orThrow: SearchError.dataLoadingFailed(url))
}