Swift

• Official Site

• Official Docs

• Style Guide

Notes

• Print to console: print("Hello, World!")

• Datatypes

  • Int: 1, 2, …
  • Float: 1.1, 1.2 …
  • Double: 1.1, 1.2 …
  • Bool: true, false
  • String: “a”, “ABC”, …
  • Find type: type(of: <value>)
  • Type-cast: <type>(<value>) Values are never implicitly converted

• Variables and Constants

  • Variable definition
    • var <name> [: <type>] = <value>
    • var someNum = 10
  • Constant definition
    • let <name> [: <type>] = <value>
    • let someNum = 10
  • _ is “don’t care”

• Operators

  • Equals: ==
  • Not equals: !=

• Strings

  • Values, not references!
  • Literal: let literalStr = "This is a literal string!"
  • Initializer: let initializerStr = String("This is an initialized string!")
  • Multiline: """ ... [\] ... """
  • Interpolation: "Variable interpolated: \(<expression>)"
  • Unicode: "Unicode: \u{xxxx}"
  • Utilities: <strName>.uppercased() <strName>.lowercased() <strName>.count()

• Data Structures

  • let | var rules follow!
  • Array
    • Index starts at 0
    • Definition: let arr = Array<<type>>() let arr: [<type>] = []
    • Utilities: <arrName>.count <arrName>.append(<val>) <arrName>.remove(at: [Int])
  • Set
    • Definition: let set = Set<<type>>() let set: Set[<type>] = []
    • Utilities: <setName>.count <setName>.insert(<val>)
  • Dictionary
    • Definition: let dict = Dictionary<<keyType>, <valType>>() let dict: [<keyType>: <valType>] = [:] Note the colon here for empty
    • Utilities: <dictName>[<key>] [ = <value> ] let original = <dictName>.updateValue(...)
  • Tuple
    • Definition: let tup = (1, 2, 3)

• Optionals

  • Values that can be nil
  • Definition: var nullableSomething: <type>? Note the ?
  • Unwrapping:
    • Force: <optionalName>! Note the !, use with caution
    • If: if <optionalName> != nil { ... }
    • Optional Binding: if let <optionalName> [= <optionalName>] { ... }
    • Null Coalesce: <optionalName> ?? <defaultValue>

• Looping

  • Iterating an array values: for <name> in <Array> { ... }
  • Iterating an array values and index: for (<name>, <idx>) in <Array>.enumerated() { ... }
  • Iterating a dict keys and values: for (<key>, <value>) in <dictName> { ... }
  • Iterate over a range from x to inclusive y: for <name> in x...y { ... }
  • Iterate over a range from x to exclusive y: for <name> in x..<y { ... }
  • while <condition> { ... }
  • repeat { ... } while <condition>

• Branching

  • if <condition> {} else {}
  • switch <name> { case <expression>: ... <default>: } No “break” required

• Functions

  • Definition:

    // Syntax:
    // fun <name>([<labelName>] <paramName>: <type>) [-> <type>] { ... }
    
    // Example 1
    func printHello() {
      print("Hello")
    }
    
    // Example 2
    func addTwoNumbers(numOne: Int, numTwo: Int) -> Int {
      numOne + numTwo
    }
    // addTwoNumbers(numOne: 1, numTwo: 2)
    
    // Example 3
    func addTwoNumbersWithDifferentNames(a numOne: Int, b numTwo: Int) -> Int {
      numOne + numTwo
    }
    // addTwoNumbersWithDifferentNames(a: 1, b: 2)
    // NOTE: Labels cannot be used inside function body
    
    // Example 4
    func addTwoNumbersWithDefaultParam(_ numOne: Int, b numTwo: Int) -> Int {
      numOne + numTwo
    }
    // addTwoNumbersWithDefaultParam(1, b: 2)
    
    // NOTE: "return" keyword is not required for single line body
    

    • Nested functions have closures (defined by {})
    • Functions are first class
    • { (<name>) in <retValue> } is like a lambda of sorts for func x(<name>: <type>) -> <retType> { return <retValue> }

• Tips

  • Get a random Int in range of x and y: Int.random(in: x...y)