Swift

Comments

// single line comment

// Swift comments support landmarks
// MARK: This is viewable in the jump bar
// TODO: Do this
// FIXME: Fix this
// MARK: - Add a separator above this

//: Single-line delimiter

/* A multi line
   comment, 
   supports **Markup**
 */
 
/*: Text on this line is not displayed in rendered markup
    This does
 */

/// A Quick Help comment
/// - warning: this function breaks sometimes
/// - parameter integer: Integer to square
/// - returns: `integer` squared

// declaration attributes
@available(iOS 10.0, macOS 10.12, *)
@available(*, introduced: 1.2, deprecated: 3.0, message: "User other")

Logging to Console

print("hello, world")
print(hello, playground, seperator: "_", terminator: "")
// can still use NSLog(str)

Simple Values

• let to make a constant
• var to make a variable

var myVar = "Hello"
let implicitInteger = 70
let implicitDouble = 70.0
let explicitDouble: Double = 70

Values are never implicitly converted to another type, need to explicitly cast them:

let label = "The width is "
let width = 94
let widthLabel = label + String(width)

String interpolation with \()

• \(#fuction) - name of the function
• \(#file) - source file
• \(#line) - line of code
• \(#column) - the columns of code

let apples = 3
let oranges = 5
let appleSummary = "I have \(apples) apples."

Multi-line strings with """, indentation before each line is removed.

"""
Hello
  Multiline
  Strings
"""

Arrays using [], access elements by index or key in brackets, comma is allowed after the last element

var shoppingList = ["water", "milk", "bread",]
shoppingList[1] = "juice"

Data Types

• Value types
  • Passed by copy
  • Implemented as structures: Integers, Floating-Points, Booleans, Characters, Strings, Arrays, Dictionaries, Tuples
  • Implemented as Enumerations: Optionals
• Reference types
  • Passed by reference
  • Classes, Functions & Closures