Swift

Question 1

Declare implicitly as type Int: var year = 2015

Answer 1

2015

Question 2

unknownString = 3

Answer 2

3 is NSObject

Question 3

unknownString = “3”

Answer 3

“3”

Question 4

If you know that the value of a variable won’t change again, you should use let. Here, myName is declared as a constant and initialized with the value Jesse: let myName = “Jesse”

Answer 4

“Jesse”

Question 5

Declare as optional (i.e. empty): var height: Int? friend = nil

Answer 5

nil nil

Question 6

To assign an optional an initial value: var friend: String? = “Joe”

Answer 6

“Joe”

Question 7

To check if there’s a vale for or optional:if let someone = friend{ print(“Hello ” + someone)}

Answer 7

“Hello Joe”

Question 8

var b = a * 3

Answer 8

15

Question 9

var c = b/2

Answer 9

2

Question 10

var c: Double = 5/2

Answer 10

2.5

Question 11

c * 2

Answer 11

5

Question 12

c * [integer 4]

Answer 12

10

Question 13

c * Double(int)

Answer 13

10

Question 14

Tuples are combined values that always appear together. Let person = (“Joe”, 24) print(person.0) print(person.1)

Answer 14

Joe 24

Question 15

Often we want to refer to members in a tuple by name rather than index value (e.g. .0, .1, .2, etc.). let (name, age) = person print(name)

Answer 15

Joe

Question 16

Tuple values may be named at the time of creation let person = (name: “Joe”, age: 24) print(person.name)

Answer 16

Joe

Question 17

Arrays are defined with brackets and commas: var arr = [1, 2, 3, 4, 5] arr = [0]

Answer 17

1

Question 18

arr.append(6) print(arr)

Answer 18

[1, 2, 3, 4, 5, 6]

Question 19

arr.removeAtIndex(2) print(arr)

Answer 19

[1, 2, 4, 5, 6]

Question 20

arr.removeLast() print(arr)

Answer 20

[1, 2, 4, 5]

Question 21

Ranges are indicated with ellipsis and their counts also begin at zero. arr.removeRange(1…2) print(arr)

Answer 21

[1, 5]

Question 22

var dict = [“name”: “Rob”, “age”: 34, “gender”: “male”] print(dict[“name”])

Answer 22

Optional(Rob)

Question 23

Use ! to force unwrap: print(dict[“name”]!)

Answer 23

Rob

Question 24

To add a value: dict[“hairColor”] = “brown”

Answer 24

{Some ‘brown’}

Question 25

var name = dict[“name”] var myString = “my name is ” + name

Answer 25

name is an NSObject (non string object)

Question 26

var myString = “my name is (name)”

Answer 26

“my name is Optional(Rob)”

Question 27

Force Unwrap var myString = “my name is (name!)”

Answer 27

“my name is Rob”

Question 28

for var i = 1; i

Answer 28

9 times

Question 29

var arr = [8, 3, 9, 91] for (index, value) in arr.enumerate() { arr[index] = value + 1 } print(arr)

Answer 29

[8, 3 , 9, 91] (4 times) [9, 4, 10, 92]/n

Question 30

var i = 1 while i

Answer 30

5 10 15 20 25 30 35 40 45 50