7 iOS Developer Interview Questions

As the world’s population increasingly relies on mobile devices to stay connected, the demand for iOS developers has skyrocketed. With the release of each new iOS update, some new features and functionalities need to be developed and maintained. Apple products are known for their sleek design and user-friendly interface, which can be attributed to the hard work of iOS developers. The pointing and clicking interface of the iPhone and iPad has become the standard for how users interact with their mobile devices, and developers play a crucial role in creating these user experiences.

If you’re interviewing for an iOS developer position, you can expect to be asked various questions about your experience, coding abilities, and problem-solving skills. Every iOS developer interview is different, but there are some common questions that you’re likely to encounter. This article will share the 7 most common iOS developer interview questions and provide examples to help you prepare for your next interview.

7 iOS Developer Interview Questions

What Is Enum Or Enumerations?

Enum or enumerations are user-defined data type that consists of a set of named values. Enumerations provide a way to organize code and make it more readable by giving names to sets of numeric values.  With enumerations, you can work with groups of related matters more meaningfully.

Enumerations in Swift are extremely flexible and can be used in various ways. They can represent simple things like directions (north, south, east, west) or more complex concepts like state machines (loading, success, failed). Enumerations can also be used to store associated values of any type, which makes them even more powerful.

The candidate should be able to explain what an enum is and how it can be used. If the candidate is unfamiliar with enumerations, they should at least be able to demonstrate a data type.

What Is A Struct and How Is It Different From A Class?

A struct is a user-defined data type that allows you to encapsulate related properties and methods. Structs are similar to classes in that they will enable you to define properties and techniques, but they are different in a few key ways. First, structs are value types, while classes are reference types. When you assign a struct to a variable, the struct is copied. With classes, a reference to the original instance is copied.

You ask the candidate how a struct differs from a class and if they are familiar with value types vs. reference types. The candidate should be able to explain the key differences between structs and classes.

Can You Define The Delegate Pattern?

The delegate pattern is a design pattern that enables an object to send messages to another object when a certain event occurs. The delegate object is typically registered with the object that generates the circumstances and implements a specific protocol or set of methods called by the event-generating object. The delegate pattern is used extensively in iOS development, and you should be familiar with it before your interview.

The professional candidate should be able to answer this question with ease. If the interviewee struggles to answer this question, it may be a sign that they are not as familiar with the delegate pattern as they should be.

Can You Explain The Difference Between An Atomic And A Non-atomic Property?

An atomic property is a property that is guaranteed to be set or retrieved atomically. This means that the property’s value will never be in an intermediate state; either it is fully set or has not been set. A non-atomic property is not guaranteed to be set or retrieved atomically, and as such, the value of the property may be in an intermediate state.

This question tests the interviewee’s knowledge of concurrency and multithreading in iOS. The red flags should go up if the candidate does not know what atomicity is or if they cannot explain the difference between atomic and non-atomic properties. It must also be included in the blockchain developer interview questions because it is a key concept in concurrent programming.

What Is The Difference Between A Frame And A Bound?

A frame is a rectangle that encloses an object’s drawing area. An object’s bounds are the rectangle with its drawing area and any space around it. In most cases, the frame and bounds rectangles will be the same size, but if an object has a shadow or some other decoration, the bounds rectangle will be larger than the frame.

This question tests the interviewee’s knowledge of Core Graphics, a key Framework used for drawing and animation in iOS. The candidate should be able to explain the difference between a frame and bounds easily.

What Is A Responder Chain?

The responder chain is a sequence of objects responsible for handling an event. The first object in the chain is the object that receives the event, and each subsequent object is responsible for managing the event if the last object does not.

The responder chain is used extensively in iOS development, and you should be familiar with it before your interview. The candidate should be able to explain what a responder chain is and how it works.

Why Would You Use An NSNotification?

An NSNotification is an object’s message to all registered observers when a specific event occurs. Notifications are used extensively in iOS development, and you should be familiar with them before your interview. Usually, the observer pattern is a better choice than notifications, but there are some circumstances where notifications are the best solution.

It is a red flag if the candidate cannot answer this question. Notifications are used extensively in iOS development, and the candidate should be familiar with them.