{"id":2675,"date":"2026-02-05T09:56:46","date_gmt":"2026-02-05T09:56:46","guid":{"rendered":"https:\/\/demo.materiamedica.net\/demo6\/?p=2675"},"modified":"2026-02-05T09:57:06","modified_gmt":"2026-02-05T09:57:06","slug":"chapter-45-swift-if","status":"publish","type":"post","link":"https:\/\/demo.materiamedica.net\/demo6\/chapter-45-swift-if\/","title":{"rendered":"Chapter 45: Swift if"},"content":{"rendered":"

1. What does if actually do?<\/h3>\n

if is the most basic decision-making tool<\/strong> in programming.<\/p>\n

It lets your code ask a yes\/no question<\/strong> and then choose what to do based on the answer.<\/p>\n

The condition inside if must be something that results in true<\/strong> or false<\/strong> (a Bool value).<\/p>\n

Basic form:<\/p>\n

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Swift<\/div>\n
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if condition {\r\n    \/\/ This code runs only when condition is true\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
Very simple first example:<\/p>\n
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Swift<\/div>\n
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let temperature = 33\r\n\r\nif temperature > 30 {\r\n    print(\"It's hot today \ud83e\udd75\")\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
If you run this code when temperature is 33 \u2192 you see the message. If you change it to 25 \u2192 nothing happens (because condition is false).<\/p>\n
2. Adding else \u2014 what to do when condition is false<\/h3>\n
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Swift<\/div>\n
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let temperature = 28\r\n\r\nif temperature > 30 {\r\n    print(\"It's hot \ud83e\udd75 \u2013 drink water!\")\r\n} else {\r\n    print(\"Nice weather \ud83d\ude0a \u2013 good for a walk\")\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
Now the code always does something<\/strong> \u2014 either the hot message or the nice weather message.<\/p>\n
3. else if \u2014 checking several possibilities<\/h3>\n
When you have more than two possible situations<\/strong>, you use else if.<\/p>\n
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Swift<\/div>\n
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let temperature = 26\r\n\r\nif temperature > 38 {\r\n    print(\"Extreme heat warning! Stay indoors \ud83c\udfe0\ud83d\udca7\")\r\n} else if temperature > 32 {\r\n    print(\"Very hot \u2013 lots of water and shade please \ud83e\udd64\")\r\n} else if temperature > 27 {\r\n    print(\"Warm and pleasant day \ud83d\ude0e\")\r\n} else if temperature > 18 {\r\n    print(\"Cool weather \u2013 light jacket \ud83e\udde5\")\r\n} else {\r\n    print(\"It's cold outside \u2744\ufe0f \u2013 wear something warm\")\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
Important rules about else if chains<\/strong>:<\/p>\n
    \n
  • Swift checks conditions from top to bottom<\/strong><\/li>\n
  • As soon as one condition is true<\/strong>, it runs that block and skips all the following ones<\/strong><\/li>\n
  • Order is very important \u2014 put the most specific \/ highest value<\/strong> conditions first<\/li>\n
  • The final else (optional) catches everything that didn’t match above<\/strong><\/li>\n<\/ul>\n
    Classic mistake example<\/strong> (very common for beginners):<\/p>\n
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    Swift<\/div>\n
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    let score = 92\r\n\r\nif score >= 80 {\r\n    print(\"A\")          \/\/ \u2190 this runs \u2192 prints \"A\"\r\n} else if score >= 90 {\r\n    print(\"A+\")         \/\/ \u2190 never reached!\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
    Correct version<\/strong>:<\/p>\n
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    Swift<\/div>\n
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    if score >= 90 {\r\n    print(\"A+\")\r\n} else if score >= 80 {\r\n    print(\"A\")\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
    4. Real-life examples \u2014 the kind of code you will write every day<\/h3>\n
    Example 1 \u2013 User login status<\/h4>\n
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    Swift<\/div>\n
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    let isLoggedIn = true\r\nlet hasPremium = false\r\n\r\nif isLoggedIn {\r\n    if hasPremium {\r\n        print(\"Welcome back, Premium member! \ud83c\udf96\ufe0f Enjoy all features.\")\r\n    } else {\r\n        print(\"Welcome back! Consider upgrading to Premium \u2728\")\r\n    }\r\n} else {\r\n    print(\"Please sign in to continue\")\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
    Example 2 \u2013 Basic age check (very common)<\/h4>\n
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    Swift<\/div>\n
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    let age = 17\r\n\r\nif age >= 18 {\r\n    print(\"You can vote \u2713\")\r\n    print(\"You can buy lottery tickets\")\r\n} else if age >= 16 {\r\n    print(\"You can get a learner's driving license\")\r\n} else {\r\n    print(\"You're still young \u2014 enjoy school! \ud83c\udf92\")\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
    Example 3 \u2013 Weather advice (classic beginner-to-intermediate exercise)<\/h4>\n
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    Swift<\/div>\n
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    let temperature = 34.5\r\nlet isRaining = false\r\n\r\nvar advice = \"\"\r\n\r\nif temperature > 38 {\r\n    advice = \"Dangerous heat! Stay indoors and drink water \ud83c\udfe0\ud83d\udca7\"\r\n} else if temperature > 32 {\r\n    advice = \"Very hot day \u2013 avoid direct sun \ud83e\udd75\"\r\n} else if temperature > 25 {\r\n    advice = \"Warm and pleasant \u2013 light clothes are fine \ud83d\ude0e\"\r\n} else if temperature > 15 {\r\n    advice = \"Cool weather \u2013 a jacket might be good \ud83e\udde5\"\r\n} else {\r\n    advice = \"It's cold outside \u2013 wear warm layers \u2744\ufe0f\"\r\n}\r\n\r\nif isRaining {\r\n    advice += \"\\nDon't forget an umbrella \u2614\"\r\n}\r\n\r\nprint(\"Weather advice for today:\")\r\nprint(advice)<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
    Example 4 \u2013 Mini grade calculator<\/h4>\n
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    Swift<\/div>\n
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    let percentage = 82.5\r\n\r\nlet grade: String\r\n\r\nif percentage >= 90 {\r\n    grade = \"A+\"\r\n} else if percentage >= 80 {\r\n    grade = \"A\"\r\n} else if percentage >= 70 {\r\n    grade = \"B\"\r\n} else if percentage >= 60 {\r\n    grade = \"C\"\r\n} else if percentage >= 50 {\r\n    grade = \"D\"\r\n} else {\r\n    grade = \"F\"\r\n}\r\n\r\nprint(\"You scored \\(percentage)% \u2192 Grade: \\(grade)\")<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
    5. Important Details & Best Practices<\/h3>\n
    Detail 1 \u2013 Condition must be Bool<\/h4>\n
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    Swift<\/div>\n
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    let age = 20\r\n\r\n\/\/ Correct\r\nif age >= 18 { \u2026 }\r\n\r\n\/\/ Wrong\r\nif age { \u2026 }           \/\/ \u274c Compile error \u2013 Int is not Bool<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
    Detail 2 \u2013 Prefer positive conditions when possible<\/h4>\n
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    Swift<\/div>\n
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    \/\/ Harder to read\r\nif !isLoggedIn { showLogin() }\r\n\r\n\/\/ Easier to read\r\nif isLoggedIn {\r\n    showDashboard()\r\n} else {\r\n    showLogin()\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
    Detail 3 \u2013 Use guard for early exit (very modern & recommended)<\/h4>\n
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    Swift<\/div>\n
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    func greetUser(user: User?) {\r\n    guard let user else {\r\n        print(\"No user provided\")\r\n        return\r\n    }\r\n    \r\n    guard user.age >= 18 else {\r\n        print(\"User is underage\")\r\n        return\r\n    }\r\n    \r\n    \/\/ happy path \u2013 user exists and is adult\r\n    print(\"Welcome, \\(user.name)!\")\r\n}<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
    guard makes code flatter<\/strong> and much easier to read<\/strong> than deep nesting.<\/p>\n
    6. Very Common Beginner Mistakes & How to Fix Them<\/h3>\n
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    \n\n\n\n\n\n\n\n\n\n
    Mistake<\/th>\nWrong code<\/th>\nCorrect \/ Better way<\/th>\nWhy?<\/th>\n<\/tr>\n<\/thead>\n
    Using = instead of ==<\/td>\nif age = 18 { \u2026 }<\/td>\nif age == 18 { \u2026 }<\/td>\n= is assignment \u2013 compile error here<\/td>\n<\/tr>\n
    Writing == true \/ == false everywhere<\/td>\nif isAdult == true { \u2026 }<\/td>\nif isAdult { \u2026 }<\/td>\nCleaner, more idiomatic<\/td>\n<\/tr>\n
    Wrong order in else-if chain<\/td>\nelse if score >= 90 { “A+” } before >=80<\/td>\nPut highest condition first<\/td>\nFirst true condition wins<\/td>\n<\/tr>\n
    Deep nesting instead of guard<\/td>\nmany nested ifs<\/td>\nUse guard + early return<\/td>\nFlatter, easier to read code<\/td>\n<\/tr>\n
    Comparing optionals directly<\/td>\nif optional == 10 { \u2026 }<\/td>\nif let value = optional, value == 10 { \u2026 }<\/td>\noptional == 10 usually means you forgot nil<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
    <\/div>\n<\/div>\n<\/div>\n
    7. Quick Reference \u2013 if patterns you will use most<\/h3>\n
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    \n\n\n\n\n\n\n\n\n\n
    Situation<\/th>\nRecommended pattern<\/th>\nExample<\/th>\n<\/tr>\n<\/thead>\n
    Simple yes\/no<\/td>\nif condition { \u2026 } else { \u2026 }<\/td>\nif isRaining { takeUmbrella() } else { walk() }<\/td>\n<\/tr>\n
    Multiple ranges \/ categories<\/td>\nif \u2026 else if \u2026 else if \u2026 else { \u2026 }<\/td>\ntemperature, grade, score ranges<\/td>\n<\/tr>\n
    Early exit \/ validation<\/td>\nguard condition else { return \/ throw \/ \u2026 }<\/td>\nguard let user else { return }<\/td>\n<\/tr>\n
    Optional unwrapping + condition<\/td>\nif let value = optional, value > 10 { \u2026 }<\/td>\nSafe optional handling<\/td>\n<\/tr>\n
    Short one-liner<\/td>\nif condition { doSomething() }<\/td>\nif isLoading { showSpinner() }<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
    <\/div>\n<\/div>\n<\/div>\n
    8. Small Practice \u2013 Try these<\/h3>\n
      \n
    1. Write weather advice code:\n
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      • \n
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        38 \u2192 “Extreme heat! Stay inside”<\/p>\n<\/blockquote>\n<\/li>\n
      • 32\u201338 \u2192 “Very hot \u2013 drink water”<\/li>\n
      • 25\u201332 \u2192 “Warm day”<\/li>\n
      • 15\u201325 \u2192 “Pleasant”<\/li>\n
      • else \u2192 “Cold”<\/li>\n<\/ul>\n<\/li>\n
      • Simple login check:\n
          \n
        • not logged in \u2192 “Please sign in”<\/li>\n
        • logged in, not premium \u2192 “Welcome! Get Premium?”<\/li>\n
        • logged in + premium \u2192 “Welcome Premium member!”<\/li>\n<\/ul>\n<\/li>\n
        • Mini grade calculator:\n
            \n
          • \u2265 90 \u2192 “A+”<\/li>\n
          • 80\u201389 \u2192 “A”<\/li>\n
          • 70\u201379 \u2192 “B”<\/li>\n
          • 60\u201369 \u2192 “C”<\/li>\n
          • below 60 \u2192 “Fail”<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n
            Paste your code here if you want feedback or want to see cleaner\/more modern versions!<\/p>\n
            What would you like to explore next?<\/p>\n
              \n
            • guard statement in depth (very important companion to if)<\/li>\n
            • switch statement (often cleaner than long if\u2026else if chains)<\/li>\n
            • if combined with optionals<\/strong> (if let, if case let, etc.)<\/li>\n
            • Conditional logic in SwiftUI<\/strong> (showing\/hiding views)<\/li>\n
            • Or move to another topic (loops, functions, arrays, optionals\u2026)<\/li>\n<\/ul>\n
              Just tell me \u2014 we\u2019ll continue in the same clear, patient, detailed style \ud83d\ude0a<\/p>\n","protected":false},"excerpt":{"rendered":"
              1. What does if actually do? if is the most basic decision-making tool in programming. It lets your code ask a yes\/no question and then choose what to do based on the answer. The...<\/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-2675","post","type-post","status-publish","format-standard","hentry","category-swift"],"_links":{"self":[{"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/posts\/2675","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=2675"}],"version-history":[{"count":1,"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/posts\/2675\/revisions"}],"predecessor-version":[{"id":2676,"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/posts\/2675\/revisions\/2676"}],"wp:attachment":[{"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/media?parent=2675"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/categories?post=2675"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/demo.materiamedica.net\/demo6\/wp-json\/wp\/v2\/tags?post=2675"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}