iOS-Xcode8-swift.md

iOS, Xcode 8, & Swift

This markdown was created as a quickstart and reference guide to getting up and productive with iOS, Xcode, and Swift.

Playground

The playground when run is code that is being stored on the memory on the computer.

Import UIKit allows us to use the features of iOS. It also includes Swift.

ViewController

When you add a Button or another object to the interface, you also need to add it to the code.

• Click the ViewController.swift and click the "Assistant Editor" button that looks like 2 circles.
• Hold control and click the object to drag it into the ViewController code.

Problem - Changing the name of an IBOutlet object after you've moved it to the code, you receive an app crash error.

• Go to your Main storyboard from the far left menu > right-click the ViewController in the submenu > and look for any yellow triangle warnings.

Functions

//: func NAME(parameter: Type, parameter2: Type2) ->(RETURN) Type { }
func calculateArea(length: Int, width: Int) -> Int {
    let area = length * width
    return area
}

let newArea = calculateArea(length: 5, width: 4)

You can use inout to modify the variable directly. Use sparingly.

var bankAccountBalance = 500.00
var newShoes = 340.00

func purchaseItem(currentBalance: inout Double, itemPrice: Double) -> Double {
    if itemPrice <= currentBalance {
        currentBalance = currentBalance - itemPrice
        print("Purchased item for: $\(itemPrice)")
    } else {
        print("You are broke, save money")
    }
}
 
let newBalance = purchaseItem(currentBalance: &bankAccountBalance, itemPrice: newShoes)

Collection Types

Section discusses "Collection Types" in Swift.

Array

Ordered list of items and can have multiple indexes with the same value.

Optionals

where was changed to a , (comma) in Swift 8.

Set

Has items that should only have one type of value. Each value needs to be unique.

Dictionary

Has keys and values. Key is certain type, value related to key. (not ordered)

A hash table is called a "Dictionary", hash maps, etc..