In real life we often have a fixed number of possible states or categories<\/strong>:<\/p>\n In old languages people usually use:<\/p>\n All of these are dangerous<\/strong> because:<\/p>\n Swift enums<\/strong> solve all of this.<\/p>\n An enum says: \u201cThis value can be one of these exact possibilities \u2014 and nothing else.\u201d<\/strong><\/p>\n The compiler forces<\/strong> you to handle every case (exhaustiveness checking).<\/p>\n That is the single most important superpower of Swift enums.<\/p>\n Key points<\/strong>:<\/p>\n Very often the state needs to carry extra information<\/strong>.<\/p>\n Real-life example<\/strong> \u2014 network \/ API response (extremely common)<\/p>\n String raw value<\/strong> (very common for API endpoints, JSON keys)<\/p>\n Pattern matching is what makes enums so powerful. You can destructure<\/strong> and extract<\/strong> associated values very elegantly.<\/p>\n Very powerful real pattern<\/strong> \u2014 unwrap + check at once<\/p>\n Paste your code here if you want feedback or want to see more elegant versions!<\/p>\n What would you like to explore next?<\/p>\n Just tell me \u2014 we\u2019ll continue in the same clear, detailed, patient style \ud83d\ude0a<\/p>\n","protected":false},"excerpt":{"rendered":" 1. Why do we even need enums? (the most important intuition) In real life we often have a fixed number of possible states or categories: The weather is either sunny, cloudy, rainy, snowy\u2026 User...<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[76],"tags":[],"class_list":["post-2734","post","type-post","status-publish","format-standard","hentry","category-swift"],"_links":{"self":[{"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/posts\/2734","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/comments?post=2734"}],"version-history":[{"count":1,"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/posts\/2734\/revisions"}],"predecessor-version":[{"id":2735,"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/posts\/2734\/revisions\/2735"}],"wp:attachment":[{"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/media?parent=2734"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/categories?post=2734"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/tags?post=2734"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}\n
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2. Basic enum \u2014 the simplest form<\/h3>\n
enum Weather {\r\n case sunny\r\n case cloudy\r\n case rainy\r\n case snowy\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\nlet today = Weather.rainy\r\n\r\nswitch today {\r\ncase .sunny:\r\n print(\"Wear sunglasses \u2600\ufe0f\")\r\ncase .cloudy:\r\n print(\"Maybe a light jacket \ud83e\udde5\")\r\ncase .rainy:\r\n print(\"Take umbrella \u2614\")\r\ncase .snowy:\r\n print(\"Wear warm coat & boots \u2744\ufe0f\")\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n
3. Enum with associated values (very powerful \u2014 real game changer)<\/h3>\n
enum Result {\r\n case success(message: String, data: [String])\r\n case failure(errorCode: Int, message: String)\r\n case loading\r\n case cancelled\r\n}\r\n\r\nlet apiResult = Result.success(message: \"Loaded\", data: [\"item1\", \"item2\"])\r\n\r\n\/\/ Pattern matching \u2014 this is where it becomes magic\r\nswitch apiResult {\r\ncase .success(let msg, let items):\r\n print(\"Success: \\(msg)\")\r\n print(\"Got \\(items.count) items\")\r\n \r\ncase .failure(let code, let msg):\r\n print(\"Error \\(code): \\(msg)\")\r\n \r\ncase .loading:\r\n print(\"Still loading\u2026\")\r\n \r\ncase .cancelled:\r\n print(\"Request was cancelled\")\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\nenum NetworkResponse {\r\n case success(statusCode: Int, data: Data)\r\n case failure(error: Error)\r\n case unauthorized\r\n case noInternet\r\n}\r\n\r\nfunc handle(response: NetworkResponse) {\r\n switch response {\r\n case .success(let code, let data):\r\n if code == 200 {\r\n print(\"Success \u2014 parsing \\(data.count) bytes\")\r\n } else {\r\n print(\"Unexpected status: \\(code)\")\r\n }\r\n \r\n case .failure(let error):\r\n print(\"Network error: \\(error.localizedDescription)\")\r\n \r\n case .unauthorized:\r\n print(\"Please sign in again\")\r\n showLoginScreen()\r\n \r\n case .noInternet:\r\n print(\"No internet connection \u2014 showing offline mode\")\r\n }\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n4. Enum with raw values (when you need to map to String \/ Int)<\/h3>\n
enum HTTPStatus: Int {\r\n case ok = 200\r\n case created = 201\r\n case badRequest = 400\r\n case unauthorized = 401\r\n case notFound = 404\r\n case serverError = 500\r\n}\r\n\r\nlet statusCode = 404\r\nif let status = HTTPStatus(rawValue: statusCode) {\r\n switch status {\r\n case .notFound:\r\n print(\"Page not found\")\r\n case .ok, .created:\r\n print(\"Success\")\r\n default:\r\n print(\"Other status: \\(status.rawValue)\")\r\n }\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\nenum Endpoint: String {\r\n case users = \"\/api\/v1\/users\"\r\n case posts = \"\/api\/v1\/posts\"\r\n case comments = \"\/api\/v1\/comments\"\r\n}\r\n\r\nlet url = baseURL + Endpoint.posts.rawValue<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n5. Pattern Matching \u2014 the real superpower of Swift enums<\/h3>\n
Basic pattern matching in switch<\/h4>\n
enum PaymentStatus {\r\n case pending\r\n case processing(amount: Double)\r\n case completed(transactionID: String)\r\n case failed(reason: String)\r\n}\r\n\r\nlet status = PaymentStatus.completed(transactionID: \"TXN-987654\")\r\n\r\nswitch status {\r\ncase .pending:\r\n print(\"Waiting for payment\u2026\")\r\n \r\ncase .processing(let amount):\r\n print(\"Processing payment of \u20b9\\(amount)\")\r\n \r\ncase .completed(let txID):\r\n print(\"Payment successful! Transaction: \\(txID)\")\r\n \r\ncase .failed(let reason):\r\n print(\"Payment failed: \\(reason)\")\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\nPattern matching in if \/ guard<\/h4>\n
if case let .completed(txID) = status {\r\n print(\"Transaction ID: \\(txID)\")\r\n}\r\n\r\nguard case let .completed(txID) = status else {\r\n print(\"Not completed yet\")\r\n return\r\n}\r\n\r\n\/\/ happy path \u2014 txID is unwrapped\r\nprint(\"Success \u2014 TX: \\(txID)\")<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\nif case let .success(data) = apiResult, data.count > 0 {\r\n process(data)\r\n} else {\r\n print(\"No data or failed\")\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n6. Very Common Real-Life Examples You Will Write<\/h3>\n
Example 1 \u2013 API response handling (probably the #1 enum use-case)<\/h4>\n
enum APIResult<T> {\r\n case success(T)\r\n case failure(Error)\r\n case loading\r\n}\r\n\r\nfunc loadUsers(completion: @escaping (APIResult<[User]>) -> Void) {\r\n \/\/ pretend network call\r\n DispatchQueue.main.asyncAfter(deadline: .now() + 1.5) {\r\n if Bool.random() {\r\n completion(.success([User(name: \"Rahul\"), User(name: \"Priya\")]))\r\n } else {\r\n completion(.failure(NSError(domain: \"Network\", code: -1009)))\r\n }\r\n }\r\n}\r\n\r\nloadUsers { result in\r\n switch result {\r\n case .success(let users):\r\n print(\"Loaded \\(users.count) users\")\r\n \r\n case .failure(let error):\r\n print(\"Failed: \\(error.localizedDescription)\")\r\n \r\n case .loading:\r\n print(\"Still loading\u2026\")\r\n }\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\nExample 2 \u2013 Navigation \/ app state (very common in SwiftUI\/UIKit)<\/h4>\n
enum ScreenState {\r\n case idle\r\n case loading(message: String)\r\n case content(data: String)\r\n case error(title: String, message: String)\r\n}\r\n\r\nfunc updateUI(for state: ScreenState) {\r\n switch state {\r\n case .idle:\r\n hideLoading()\r\n hideError()\r\n showIdleView()\r\n \r\n case .loading(let msg):\r\n showLoading(message: msg)\r\n \r\n case .content(let data):\r\n hideLoading()\r\n showContent(data)\r\n \r\n case .error(let title, let msg):\r\n hideLoading()\r\n showError(title: title, message: msg)\r\n }\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n7. Quick Summary \u2013 When to use what<\/h3>\n
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\n \nSituation<\/th>\n Use this kind of enum<\/th>\n Typical example<\/th>\n<\/tr>\n<\/thead>\n \n Simple fixed states<\/td>\n enum Direction { case north, south, east, west }<\/td>\n UI states, weather, roles<\/td>\n<\/tr>\n \n State + extra data<\/td>\n case success(data: T)<\/td>\n API responses, async results<\/td>\n<\/tr>\n \n Error with details<\/td>\n case failure(code: Int, message: String)<\/td>\n Network, validation errors<\/td>\n<\/tr>\n \n Raw value needed (String\/Int)<\/td>\n enum HTTPStatus: Int { case ok = 200 \u2026 }<\/td>\n API codes, persistence<\/td>\n<\/tr>\n \n Need exhaustive checking<\/td>\n switch without default on enum<\/td>\n Compiler forces you to handle all cases<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n 8. Small Practice \u2013 Try these<\/h3>\n
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