Swift

Question 1

Escape variable from a string

Answer 1

“Model is (model)”

Question 2

variable vs const

Answer 2

var and let

Question 3

what are the data types

Answer 3

Int, Double, Float, String, Bool

Question 4

Define a tuple, and access the second value

Answer 4

let myTuple = (1, 15, “Test”)
var val = myTuple.1

Question 5

Deconstruct a tuple.

Answer 5

let (x, _, z) = myTuple

Question 6

Define a tuple with variable names, and access the second value

Answer 6

let myTuple = (first: 1, second: 2, str: “test”
var val = myTuple.second

Question 7

What happens when using a variable that has a non-optional type, but hasn’tbeen assigned a value?

Answer 7

An error stating that the value is being used before being initialized.

It is not nil.

Question 8

Define an optional Int and use it

Answer 8

let x: Int?
if (x != nil) {
print(x!)
}

Question 9

Unwrap multiple optionals

Answer 9

if let x = opt1, let y = opt2, let z = opt3 {
}

Question 10

Difference between Int? and Int! when declaring variables

Answer 10

? requires forced unwrapping. AKA using myVal! when accessing or using let x = myVal in if condition.
! means it is implicitly unwrapped and can be used without checking if nil

Question 11

Can var myString: String = nil be used?

Answer 11

No, only optionals can be nil

Question 12

Upcast UIButton to UIControl

Answer 12

let myControl = myButton as UIControl

Question 13

Downcast UIScrollView to UITextView

Answer 13

if let myTextView = myScrollView as ? UITextView {
}

Question 14

CHeck if something is a Class

Answer 14

if myObj is Class {
}