Swift V2

Question 1

What kind of comment is signified by a //:

Answer 1

Rich text. You can turn on rendering of comments in XCode which will give it a HTML like appearance

Question 2

How do you declare a new variable?

Answer 2

var foobar = 10;

Question 3

How do you specify a type of variable?

Answer 3

var foobar : String = “foobar”;

Question 4

Do you need to put semicolons in code?

Answer 4

No - they are not required.

Question 5

What is wrong with the following code?

var foobar =”chicken”;

Answer 5

There is not space after the assignment operator, and there is a space before. These have to be balanced. I.e. if you have a space before, you need one after, and if you don’t have a space before, you shouldn’t have one after.

Question 6

How do you declare a constant?

Answer 6

You use the let keyword.

let str2 = “chicken”;

Question 7

Is there are a benefit to using constants?

Answer 7

Yes, there is a slight memory improvement.

Question 8

Does swift using GC?

Answer 8

Yes, it uses automated reference counting.

Question 9

What are two ways to concatenate the strings:

let firstName = "Cain";
let lastName = "Martin";

Answer 9

let name = "\(firstName) \(lastName)"; \\ Interpolation
let name = firstName + " " + lastName; \\ Concatenation

Question 10

What is wrong with the following code?

var a = 5;
a = 5.0;

Answer 10

Once you have set the type (by assigning a value of a specific type to the variable) - it cannot be changed.

Question 11

How do you declare a float, given that floats and doubles look the same?

Answer 11

You have to be explicit - it will default to double.

var c : Float = 10.0;

Question 12

Why is swift considered type safe?

Answer 12

Because you cannot change the type of or put in unexpected types in a variable.

Question 13

What is wrong with the following code?

var a = 10.0;
var b : Float = 4.2;
var c = a + b;

Answer 13

You can’t add two numbers of different types, you must cast the value first.

var c = a + Double(b);

Question 14

What kind of markup does the rich text comments use?

Answer 14

Markdown

Question 15

How would you make a heading with h2’s and h3’s in the rich text comments?

Answer 15

/*: This text doesn't show up
 # This is a h1
 ## This is a h2
 ### This is a h3
This would be normal text
*/

NOTE: Don’t forget the colon after the opening of the comment.

Question 16

How would you add bulleted list to the rich text comments?

Answer 16

/*: This text doesn't show up
 * This is a bullet
 * This is also a bullet
This text just shows up normally
*/

NOTE: Don’t forget the colon after the opening of the comment.

Question 17

What is unusual about the if / else statements of Swift?

Answer 17

They don’t require the parenthesis. i.e.

if x == y {
}

NOTE: You can use the parenthesis though if you want

Question 18

How do you declare a boolean?

Answer 18

var isABool: Bool;

Question 19

Does swift have a === operator?

Answer 19

No - just the standard equality test operator - ==

Question 20

Write a print statement that includes the value of a variable named x using interpolation.

Answer 20

print (“The value of x is (x), fool”)