50 Swift Interview Questions and Answers

Ace your iOS developer job interview by knowing the answers to these essential questions

Original Image: Charles Deluvio

Here’s a list of 50 Swift interview questions and answers. These questions focus on Swift programming and iOS app development. You need to know the answers to these before you get a chance to show your skills in front of a job interviewer.

These questions are in no particular order — let’s get right into it!

1. What Causes an Error? How Can You Fix It?

let n1: Int = 1
let n2: Float = 2.0
let n3: Double = 3.34
var result = n1 + n2 + n3

Answer:

In Swift, implicit type casting between two data types is not possible.

In the code above, you’re trying to add three elements together, each of which represents a different data type.

To fix this, you need to convert each value to the same data type. For example:

var result = Double(n1) + Double(n2) + n3

2. What is the Value of Len? Why?

var arr1 = [1, 2, 3]
var arr2 = arr1
arr2.append(4)
var len = arr1.count