We have surely heard the abbreviation iOS many times. iOS is the abbreviation for “iPhone Operating System.” The operating system is used by Apple devices, and is regarded as the second most widely used mobile operating system worldwide in the world, following Android. The operating system is the basis for several Apple products, such as iPhone, iPad and iPod. iPhone, iPad, and iPod. iOS is well-known for its easy and user-friendly interface. Last 14 years have seen several jobs being created for iOS Development. It has become one of the most lucrative software development jobs. I talked to several senior iOS developers and created a list of common iOS interview questions that you can go through before you appear in an iOS Interview.
Common iOS Interview Questions
Q1. What’s Swift? Give a brief explanation of some characteristics
Swift, a contemporary programming language that was introduced in June 2014 by Apple Inc. in June 2014.
- Rapid (static process dispatch)
- The Safe (type safe)
- Friendly syntax (more precise than objective-c)
Certain key features are distinctive and powerful: generics closures, tuples, and type inference can be used in conjunction with each other.
Q2. What’s the distinction between static or dynamic typing?
Swift utilises static typesetting, and could result in a compiler error. Objective-C utilises dynamic typing, that checks for type during the time of running. It means the program is able to be compiled even if it has bugs that block the program from running correctly.
Q3. What are generics?
A type that can accept any type. It is safe for type that means that the compiler will not complain at the time of compilation. For instance, if we send a string to an unspecified type and then utilise it as an integer, a compiler-time error will occur. This is beneficial because you can detect errors before they happen.
Q4. What are protocols?
Protocols are interfaces which means it includes abstractions, methods and constants and variables. Protocols share functionality among classes. It is possible to implement several protocols.
Q5. How do you achieve volatility? How is volatility achieved in Swift or Objective-c?
In Swift it is possible to define a constant as an unchanging value, while variables are modified. It is determined by the time the variable is created using the keyword “initiate”, not the specific class of data.
The mutability feature in Objective-C can be limited to a specific class. In this case, for example, you have to make use of the NSMutableArray class in order to modify the size of the array.
Q6. What are subscripts?
Subscripts are shortcuts for accessing member elements of a collection, list, or sequence.
Q7. What is the difference between Any Object and Generics?
AnyObject doesn’t specify any kind of type, and allows you to pass any type of data, which could result in an error at runtime (which is a bad thing). When using generics, you have to define the type, and it won’t allow you to pass if you input the wrong type during the time of compilation (which is fine).
Q8. What is GCD? How is it used?
This framework is provided by Apple, which handles multiple threads. It is utilised for working on the asynchronous task. For instance, if you need to retrieve information from an API, GCD can be used to complete fetch tasks at a time.
Q9. What is Auto Layout?
It’s a system within xCode that calculates dynamically the dimensions and positions of every view according to the constraints put on these views.
Q10. What happens when you call a method on a nil pointer in Objective-C?
This is referred to as inaction (no action). It will execute the next instruction. It will not return null or 0.
Q11. What is the difference between NSArray and NSMutable?
NSArray is used when you don’t want to resize or change the data stored in the array. In the NSMutable array, you can add, remove, or change the values in the array.
Q12. What is a delegate pattern?
“A delegate is an object that acts on behalf of or in coordination with another object when that object encounters an event in the program.” © Apple
Q13. What is a category in Swift?
Categories is an Objective C term for rapid expansion. You can also extend the closure beyond the class. You must name the extension/category in objective-c.
Q14. What is the use of KVC or Key-value coding?
KVC can be used to gain access to a property or value using a string.
Q15. What are the most important certificates to issue and develop apps for Android or iOS?
The certificate types are:
- Development Certificate
- Distribution Certificate
- Development and Distributing Certificates
Q16. What is the difference between retaining and copying?
The retain count of an object is increased by one when it is retained. The object’s instance is stored in memory until its retain count drops below zero. The instance’s reference is kept in memory and shared with all who have it. Copy means that an object is copied with a duplicated value. However, it cannot be shared with any other person.
Q17. Give a brief about the singleton pattern
The Singleton pattern is a design pattern that ensures only one instance exists for a given class and that instance has a global access point. When needed for the first time, it generally uses lazy loading to create a single instance.
If you have some more questions about an iOS interview, please add them to the comments section below. I will try to add those questions in this blog. If you want to read more questions, you can visit this blog.. https://ducknowl.com/top-ios-interview-questions-and-answers/