Value types<\/strong><\/td>\n| Int, Double, Bool, String, Array, Dictionary, Set, struct, enum<\/td>\n | A copy<\/strong> is made (independent)<\/td>\n| Most everyday types \u2014 safe & predictable<\/td>\n<\/tr>\n | \nReference types<\/strong><\/td>\n| class, objects that inherit from NSObject, some closures<\/td>\n | Only a reference<\/strong> is copied (shared)<\/td>\nUsed for shared state (like view controllers)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n Beginner rule (very important):<\/strong><\/p>\n\nIn 95% of beginner and intermediate code you will mostly meet value types<\/strong> You will see class later (UIKit, SwiftUI view models, networking models sometimes)<\/p>\n<\/blockquote>\n3. The most important built-in data types (with examples)<\/h3>\nLet\u2019s go through them one by one \u2014 with code you can run right now.<\/p>\n 3.1 Integer types (Int, UInt, Int64, \u2026)<\/h4>\n\n \n \n Swift<\/div>\n \n let age = 25 \/\/ Int (most common)\r\nlet likes = 1_245_678 \/\/ underscore makes big numbers readable\r\nlet negativeBalance = -150\r\nlet veryBigNumber = 9_223_372_036_854_775_807 \/\/ Int.max on 64-bit\r\n\r\nlet smallCounter: UInt8 = 255 \/\/ only 0...255\r\nlet fileSizeBytes: Int64 = 8_589_934_592 \/\/ when you need exactly 64-bit<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\nQuick table \u2013 integer types you might meet<\/strong><\/p>\n\n \n \n\n\n| Type<\/th>\n | Range (approx)<\/th>\n | Signed?<\/th>\n | Typical use case<\/th>\n<\/tr>\n<\/thead>\n | \n\n| Int<\/td>\n | -9 quintillion \u2026 +9 quintillion<\/td>\n | Yes<\/td>\n | Normal counting, IDs, indices (default)<\/td>\n<\/tr>\n | \n| UInt<\/td>\n | 0 \u2026 18 quintillion<\/td>\n | No<\/td>\n | Rarely \u2014 when you really want non-negative<\/td>\n<\/tr>\n | \n| Int64<\/td>\n | -9 quintillion \u2026 +9 quintillion<\/td>\n | Yes<\/td>\n | Large file sizes, timestamps<\/td>\n<\/tr>\n | \n| UInt8<\/td>\n | 0 \u2026 255<\/td>\n | No<\/td>\n | Colors (RGB), small counters<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n 3.2 Floating-point types (Double vs Float)<\/h4>\n\n \n \n Swift<\/div>\n \n let height = 1.72 \/\/ Double \u2013 most common choice\r\nlet temperature = 36.6\r\nlet pi = 3.141592653589793\r\nlet verySmallNumber = 1.23e-6 \/\/ scientific notation\r\n\r\nlet opacity: Float = 0.75 \/\/ 32-bit float \u2013 less precise<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\nVery important rule most beginners miss:<\/strong><\/p>\n\nUse Double<\/strong> for almost everything Use Float<\/strong> only when:<\/p>\n\n- You need to save memory (very rare)<\/li>\n
- You are working with old APIs \/ graphics that expect Float<\/li>\n<\/ul>\n<\/blockquote>\n
3.3 Money \u2013 special case: Decimal (not Double!)<\/h4>\n\n \n \n Swift<\/div>\n \n import Foundation\r\n\r\nlet itemPrice: Decimal = 1499.99\r\nlet quantity: Int = 3\r\nlet taxRate: Decimal = 0.18\r\n\r\nlet subtotal = itemPrice * Decimal(quantity)\r\nlet tax = subtotal * taxRate\r\nlet total = subtotal + tax\r\n\r\nprint(total) \/\/ 5311.9702<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\nWhy not Double for money?<\/strong><\/p>\n\n \n \n Swift<\/div>\n \n let bad = 0.1 + 0.2 \/\/ 0.30000000000000004 \u2190 floating point error!\r\nlet good: Decimal = 0.1 + 0.2 \/\/ exactly 0.3<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\nRule:<\/strong> Double \u2192 measurements, coordinates, animations Decimal \u2192 money, prices, financial calculations<\/p>\n3.4 Boolean (Bool)<\/h4>\n\n \n \n Swift<\/div>\n \n let isLoggedIn = true\r\nlet hasPremium = false\r\nlet isRaining = false\r\nlet canSubmitForm = emailIsValid && passwordMeetsRequirements<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\nVery often used in conditions:<\/p>\n \n \n \n Swift<\/div>\n \n if isLoggedIn {\r\n showDashboard()\r\n} else {\r\n showLoginScreen()\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n3.5 Text (String \u2013 very important!)<\/h4>\n\n \n \n Swift<\/div>\n \n let name = \"Rahul Verma\"\r\nlet greeting = \"\u0c28\u0c2e\u0c38\u0c4d\u0c24\u0c47 Hyderabad! \ud83c\udf36\ufe0f\"\r\nlet multiline = \"\"\"\r\n First line\r\n Second line\r\n Third line with emoji \ud83d\ude3a\r\n \"\"\"\r\n\r\nlet empty = \"\"\r\nlet singleCharString = \"A\" \/\/ still String, not Character<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\nUseful things you do every day:<\/p>\n \n \n \n Swift<\/div>\n \n print(name.count) \/\/ 11\r\nprint(name.uppercased()) \/\/ RAHUL VERMA\r\nprint(name.hasPrefix(\"Rah\")) \/\/ true\r\nprint(name.contains(\"ul\")) \/\/ true\r\nprint(greeting.contains(\"\ud83c\udf36\ufe0f\")) \/\/ true<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n3.6 Single character (Character) \u2013 rare<\/h4>\n\n \n \n Swift<\/div>\n \n let grade: Character = \"A\"\r\nlet currency: Character = \"\u20b9\"\r\nlet smile: Character = \"\ud83d\ude0a\"\r\n\r\n\/\/ This is NOT a Character \u2014 it's a String!\r\nlet wrong = \"A\" \/\/ String with one character<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\nRule of thumb:<\/strong> You almost never need Character \u2014 use String even for single letters\/symbols.<\/p>\n4. Quick real-life examples \u2013 how types appear in apps<\/h3>\n\n \n \n Swift<\/div>\n \n struct Product {\r\n let id: String \/\/ or UUID\r\n let name: String\r\n let price: Decimal \/\/ money!\r\n let rating: Double \/\/ 4.78\r\n let reviewCount: Int\r\n let inStock: Bool\r\n let tags: [String] \/\/ we'll talk about Array later\r\n}\r\n\r\nlet iphone = Product(\r\n id: \"MNH63HN\/A\",\r\n name: \"iPhone 16 Pro\",\r\n price: 119900,\r\n rating: 4.85,\r\n reviewCount: 12450,\r\n inStock: true,\r\n tags: [\"smartphone\", \"apple\", \"5G\"]\r\n)<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n5. Very common beginner mistakes<\/h3>\n\n \n \n\n\n| Mistake<\/th>\n | Wrong code<\/th>\n | Correct approach<\/th>\n | Why?<\/th>\n<\/tr>\n<\/thead>\n | \n\n| Using Float for normal decimals<\/td>\n | let price: Float = 99.99<\/td>\n | let price = 99.99 \/\/ Double<\/td>\n | Double is much more precise<\/td>\n<\/tr>\n | \n| Using Double for money<\/td>\n | let total = 123.45 + 0.01<\/td>\n | let total: Decimal = 123.45 + 0.01<\/td>\n | Floating-point rounding errors<\/td>\n<\/tr>\n | \n| Forgetting String is value type<\/td>\n | Expecting shared mutation<\/td>\n | var a = b; a += “!” \u2192 b unchanged<\/td>\n | Value types are copied<\/td>\n<\/tr>\n | \n| Using Int32 \/ UInt32 everywhere<\/td>\n | let count: Int32 = 100<\/td>\n | let count = 100 \/\/ Int<\/td>\n | Int is the normal choice<\/td>\n<\/tr>\n | \n| Declaring single letters as Character<\/td>\n | let letter: Character = “A” everywhere<\/td>\n | let letter = “A”<\/td>\n | String is more flexible<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n 6. Summary table \u2013 most common types in real apps<\/h3>\n\n \n \n\n\n| Purpose<\/th>\n | Recommended type<\/th>\n | Example value<\/th>\n<\/tr>\n<\/thead>\n | \n\n| Counting, indices, IDs<\/td>\n | Int<\/td>\n | userCount = 1420<\/td>\n<\/tr>\n | \n| Money, prices, financial<\/td>\n | Decimal<\/td>\n | price = 2499.99<\/td>\n<\/tr>\n | \n| Measurements, coordinates, science<\/td>\n | Double<\/td>\n | temperature = 36.6<\/td>\n<\/tr>\n | \n| True \/ false flags<\/td>\n | Bool<\/td>\n | isPremium = true<\/td>\n<\/tr>\n | \n| Text, names, messages, JSON<\/td>\n | String<\/td>\n | username = “sneha_dev”<\/td>\n<\/tr>\n | \n| Single symbol (rare)<\/td>\n | Character<\/td>\n | currency = “\u20b9”<\/td>\n<\/tr>\n | \n| Very large numbers<\/td>\n | Int64 \/ UInt64<\/td>\n | fileSizeBytes = 8_589_934_592<\/td>\n<\/tr>\n | \n| Small counters \/ bytes<\/td>\n | UInt8<\/td>\n | red: UInt8 = 255<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n Which data type or group would you like to explore much deeper<\/strong> next?<\/p>\n\n- String in much more detail (very important)<\/li>\n
- Decimal vs Double \u2013 with real money examples<\/li>\n
- Collections (Array, Dictionary, Set)<\/li>\n
- Optionals (Int?, String?, nil)<\/li>\n
- Or start with structs & enums<\/li>\n<\/ul>\n
Just tell me \u2014 we\u2019ll continue in the same slow, clear, teacher-like style \ud83d\ude0a<\/p>\n","protected":false},"excerpt":{"rendered":" 1. What is a data type? (very simple explanation) A data type tells the computer: What kind of value this is (number, text, true\/false, list, \u2026) How much memory it needs What operations are...<\/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-2616","post","type-post","status-publish","format-standard","hentry","category-swift"],"_links":{"self":[{"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/posts\/2616","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=2616"}],"version-history":[{"count":1,"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/posts\/2616\/revisions"}],"predecessor-version":[{"id":2617,"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/posts\/2616\/revisions\/2617"}],"wp:attachment":[{"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/media?parent=2616"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/categories?post=2616"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/tags?post=2616"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}} | |
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