If you are starting the hiring process, either as a candidate or an interviewer, here is a list of 10 comprehensive and essential IOS interview questions to keep in mind in your quest to find the perfect iOS developer or the perfect IOS job.!
10 iOS Interview Questions: for Junior, Mid – Level and Senior Developers
Based on the stage of your project and the company’s strategy, there is one last thing to consider. An iOS developer follows the app development from the beginning to the end. When it comes to hiring iOS developers, remember that their expertise and proficiency with tools depend on their years of experience. If you want an iPhone developer to manage the launch of a new app, you want to look for a Senior developer. To join and support an existing team, you can hire a Junior or Middle position focussing on a specific stage of the process.
Junior iOS Developer Interview Questions: Less Than 2 Years Experience
1. What is Cocoa and Cocoa Touch?
2. What are Swift and Objective-C?
Objective-C is the primary programming language to write OS X and iOS software. As a superset of the C programming language, it provides object-oriented capabilities and a dynamic runtime. Objective-C manages the syntax, primitive types, and flow control statements of C, adding syntax for classes and methods. It is language-level support for object graph management and objects literals that provide dynamic typing and binding.
Swift is a new programming language for Apple apps that builds on the best of C and Objective-C without C compatibility constraints. Swift adopts safe programming patterns and adds modern features to make programming easier, more flexible, and more fun (Apple developer library).
3. What is an autorelease pool?
When you send autorelease to an object, it adds to the innermost autorelease pool, and when this pool is drained, it simply sends releases to the other objects in the pool. Autorelease pools allow sending release in several places – the most common in Cocoa GUI apps is at the end of the current run loop cycle.
Middle-Level iOS Developer Interview Questions: Between 2 And 5 Years
1. Which JSON frameworks does iOS support?
iOS supports the SBJson framework, a JSON parser and generator for Objective-C providing flexible APIs and additional control.
2. How do you achieve currency in iOS?
The three ways to achieve iOS currency are threads, dispatch queues, and operation queues.
3. Which framework can construct an iOS app’s user interface?
The UIKit framework provides event handling, drawing model, windows, views, specific control for touch screen interfaces.
Senior iOS Developer Interview Questions: More Than 5 Years
1. What are the main features and advantages or disadvantages of Swift?
Swift is a typing language allowing protocols and generics. Static typing offers compile-time warnings and compilation errors while providing better runtime safety and determinism.
This strict type of safety works better in the following scenarios:
- Building a client application with more strict explicitness rather than dynamism
- Working in an environment restricting less experienced developers (beginners and juniors)
- Refactoring your code, the compiler is an aid to write clean code
When you are building a library or a framework, static typing can be too restrictive. In this case, Objective-C is a better choice because it allows better meta-programming capabilities.
2. How do you handle memory management in iOS?
Similarly to Objective-C, Swift uses Automatic Reference Counting (ARC). ARC records strong references to instances of classes. When you assign or unassign instances of classes, or reference types, to constants, properties, and variables, the instances increase or decrease their reference. The software deallocates the object’s memory when the reference count drops to zero. When assigned, the reference count of value types is copied. If you don’t specify otherwise, all the references are considered strong references.
3. What is MVC?
MVC, Model View Controller, is a software design pattern Apple uses for iOS application development. Models represent application data, views create items on the screen, and controllers monitor and manage the data flow between model and view. The latter never communicate directly with each other. Since view controllers handle the workflow, the code is rigid and hard to change. You can always rely on other design patterns such as MVVM, MVP, or Coordinator. Also, frameworks like VIPER and RIBs are specifically developed to scale iOS code and avoid Massive View Controller issues.
Now You’re Ready
Communication and collaborative skills are crucial, as much as technical skills. Pay attention to their personality and interactions during the interview process. Some things can’t be spotted on a CV! And on the other hand, if you’re a job seeker, please note that by improving your communication skills, you can always add 10% to your salary offer.
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