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Swift

iOS macOS apps safe systems and modern Apple development

English

Definition first

What Swift means

Swift is a programming language for writing exact instructions, often used for iOS macOS apps safe systems and modern Apple development. Start with one mental model: input goes through steps and becomes output.

Minimum run factsFile main.swiftRun swift main.swiftHabit Use optionals deliberately and keep playground examples small
Program

An ordered set of instructions. It reads input, follows rules, and produces output.

Value and variable

A value is data. A variable is the name you use to hold and reuse that data.

Function

A named piece of work. It takes input, does one job, and can return a result.

Runtime

Swift toolchain is the place that actually runs code from main.swift.

First readable code

Program output

entry point output syntax print
print(42)
Output 42

Language lineage

Swift family tree

See where Swift comes from, which languages feel close, and what to learn next.

roots
Objective-CRustHaskell
currentSwiftApple systems family
familyApple systems family
best used for

iOS, macOS, Apple apps, and modern client architecture

Zero base path

1Read one rule2Predict output3Type from memory4Run checklist5Repeat with one change

Question bank

Search before practice

Pick a stage or search across the open programming bank. Jump straight to the matching drill.

18 matching questions
Q 1ChoiceStage 1 definitions

Swift practice 1

Swift question 1. Choose the statement that matches printing a value.

Q 2ChoiceStage 1 definitions

Swift practice 2

Swift question 2. Choose the statement that matches naming a value.

Q 3ChoiceStage 1 definitions

Swift practice 3

Swift question 3. Choose the statement that matches reusable function.

Q 4ChoiceStage 1 definitions

Swift practice 4

Swift question 4. Choose the statement that matches basic collection.

Q 5ChoiceStage 1 definitions

Swift practice 5

Swift question 5. Choose the statement that matches printing a value.

Q 6ChoiceStage 1 definitions

Swift practice 6

Swift question 6. Choose the statement that matches naming a value.

Q 7ChoiceStage 1 definitions

Swift practice 7

Swift question 7. Choose the statement that matches reusable function.

Q 8ChoiceStage 1 definitions

Swift practice 8

Swift question 8. Choose the statement that matches basic collection.

Q 9ChoiceStage 1 definitions

Swift practice 9

Swift question 9. Choose the statement that matches printing a value.

Q 10ChoiceStage 1 definitions

Swift practice 10

Swift question 10. Choose the statement that matches naming a value.

Q 11ChoiceStage 1 definitions

Swift practice 11

Swift question 11. Choose the statement that matches reusable function.

Q 12ChoiceStage 1 definitions

Swift practice 12

Swift question 12. Choose the statement that matches basic collection.

Q 13ChoiceStage 1 definitions

Swift practice 13

Swift question 13. Choose the statement that matches printing a value.

Q 14ChoiceStage 1 definitions

Swift practice 14

Swift question 14. Choose the statement that matches naming a value.

Q 15ChoiceStage 1 definitions

Swift practice 15

Swift question 15. Choose the statement that matches reusable function.

Q 16ChoiceStage 1 definitions

Swift practice 16

Swift question 16. Choose the statement that matches basic collection.

Q 17ChoiceStage 1 definitions

Swift practice 17

Swift question 17. Choose the statement that matches printing a value.

Q 18ChoiceStage 1 definitions

Swift practice 18

Swift question 18. Choose the statement that matches naming a value.

Multiple choice

Swift practice 1

Q 1Choicenew

Swift question 1. Choose the statement that matches printing a value.

print(42)

Reference

Patterns for main.swift

Swift toolchainswift main.swift
Recall from memoryRead a small point then write it back without looking
Trace the codeWrite variable values line by line before you run the answer
Type it yourselfCopy less type more and fix one small error at a time

entry point output syntax print

Program output

print(42)
  • Run the smallest file first
  • Print one known value
  • Check the output before adding more code

variables assignment types let

Values and names

let total = 42
print(total)
  • Give values readable names
  • Keep one idea per line while learning
  • Trace the value before changing it

function collection Array

Functions and collections

func add(_ a: Int, _ b: Int) -> Int {
  return a + b
}

let scores = [40, 2]
print(scores.count)
  • Keep functions small
  • Return useful values
  • Use the common collection before reaching for frameworks