Swift Programming Syntax

Front 1

Create a Type Inference variable

Back 1

var string = "abc"

var number = 123

Hint 1

Providing a value when creating a variable or constant lets the compiler infer its type.

Front 2

var number = 123

Print above using String Interpolation

Back 2

print("\(number)")

Hint 2

Write Int values in \() and the value be converted into a string

Front 3

Declare name as an Optional

Back 3

var name: string?

Hint 3

A value that contains either an underlying value or nil to indicate that the value is missing

Swift disallow assigning nil to prevent null pointer exceptions.

Front 4

var optionalValue: Int?

User Optional Binding to check if optionalValue has a value.

Back 4

if let value = optionalValue{

value = optionalValue*2

} else {

print("Optional has a nil value.")

}

Hint 4

The safest way to unwrap an optional. Use a If let... else... statement to check if a optional has a value or a nil.

Front 5

var imageView = UIImageView()

imageView.image = UIImage(named:"puppy_in_box")

Use Optional Chaining to check if size has a value and print the value.

Back 5

if let imageSize = imageView.image?.size{

print("\(imageSize)")

} else {

print("Image has not been set.")

}

Jnj

Hint 5

A process of querying and calling properties, methods, and subscript on an optioned that might currently be nil.

Front 6

Create an Implicitly Unwrapped Optional

Back 6

var x: int!

Hint 6

Optionals that is clear that it will always have a value after that value is first set.

Front 7

Var DogName: String?

Force unwrap DogName

Back 7

DogName!

Hint 7

Once you’re sure that the optional does contain a value, you can access its underlying value by adding an exclamation mark (!) to the end of the optional’s name.

Front 8

Create a class called Vehicle with a stored property called currentSpeed set to 0.0

Back 8

class Vehicle{

var currentSpeed = 0.0

}

Hint 8

Classes are general-purpose, flexible constructs that become the building blocks of your program’s code.

Front 9

Create a sub-class of the class Vehicle called Bicycle with a stored property called hasBasket set to false

Back 9

class Bicycle: Vehicle {

var hasBasket = false

}

Hint 9

Subclassing is the act of basing a new class on an existing class. The subclass inherits characteristics from the existing class, which you can then refine. You can also add new characteristics to the subclass.

Front 10

var numericalString = "3"

var number =

Declare number by converting it using a built-in function

Back 10

var number = int(numericalString)

Hint 10

This is new to Swift 2.

Front 11

Initialize an array called cuteAnimals with the type CuddlyCreature.

Back 11

var cuteAnimals =[CuddlyCreature]()

Front 12

Initialize a string array of 5 US states using array literal syntax.

Back 12

let states = ["Florida", "Idaho", "Maine", "Kansas", "Virginia"]

Front 13

var colors = ["red", "orange", "yellow", "green", "blue", "violet"]

Insert indigo after blue

Back 13

colors.insert("indigo", atIndex: 5)

Front 14

Initialize an empty dictionary which holds Strings as keys and Bools as values

Back 14

var emptyDict = [String:Bool]()

Front 15

Initialize a dictionary using array literal syntax

Back 15

var goodfood = ["apple":true, "Torula Yeast":false]

Front 16

Why does this code return an optional?

CityStateDict["New York"]

Back 16

There is a possibility this code is looking for something that is not in the dictionary, resulting in nil, thus requiring a return of an optional.

Front 17

Write the syntax for creating a range.

Back 17

1...10

Front 18

Create a for-in loop for this array.

var numarray = [2, 4, 6, 8]

Back 18

For number in numarray{

print(number)

}

Front 19

Create a for-in loop for this dictionary array.

var treetype = ["cedar":true, "birch": true, "licorice":false]

Back 19

for (tree, tfval) in treetype{

if tfval{

print(tree + "is a tree.")

} else{

print(tree + "is not a tree.")

}

}

Front 20

Replace "123" in below string with "911"

var string = "12345"

Back 20

string.stringByReplacingOccurencesOfString("123", withString: "911")

Front 21

Create an enumeration called tree for the following: leaves, branches, roots.

Back 21

enum tree{

case leaves, branches, roots

}

Front 22

Create switch statement for each case.

enum tree{

case leaves, branches, roots

}

var gathering = tree.leaves

Back 22

switch gathering{

case .leaves:

print("I'm gathering leaves.")

case .branches:

print("I'm gathering branches.")

case .roots:

print("I'm gathering roots.")

}

Front 23

Create a switch-case control flow to change grade to "Pass", "Fail" or "Incomplete"

var score = 75

var grade = ""

Back 23

switch score{

case 65...100:

grade = "Pass"

case 0...64:

grade = "Fail"

default:

grade = "Incomplete"

}

Front 24

What are the 3 different functions in Swift?

Back 24

Global Functions (ex: Print), Nested Functions (function within a function), Methods (functions in a class).