iOS Q&A

1.   Difference between SEL and @selector.

2.   Difference between retain and copy? (The answer that I am looking for is memory wise and not some answer googled here and there)

3.   Difference between categories and extension?

4.   Explain responder chain? And how it works

5.   Difference between method calling and performSelector? What's the difference when you call a method using self and @selector

6.   When to use strong and weak reference?

7.   Why are IBOutlets and delegates declared as weak and not strong? And describe a case where you would declare delegates as strong

8.   Difference between atomic and non-atomic, Is atomic thread safe if YES then why YES and if NO then why NO?

9.   Explain sandboxing in iOS app?

10.  How to upload an enterprise app without using any third party tool?

11. Difference between Core Data and SQLITE? (Note : Mostly people are asking how both work in a multi threading environment so be prepared accordingly)

12. How does a table cell work?

13. In ARC how does the compiler know that a certain object is not required?

14. Why and when do we make use of blocks in our code?

15. How does an SSL certificate work?

16. What will you use storyboard or XIB’s and why?

17. How will you convert an iOS 6 app to iOS 7?

18. What does code signing mean?

19. Explain toll-free bridging in iOS?

20. Explain the life cycle of a ViewController?

21. Explain life cycle of an iOS app?

22. What is the use of self = [super init]?

23. Sizes of the entire iphone and ipad screen?

24. Difference between NSURLConnection and NSURLSession?

25. Better to read some new features in the latest SDK.

26. You need to call a webservice and lets say your app is in background for 2 days how will you achieve this in iOS 6?

27. How will the user submit you crash report of your app, all you have provided is just the email of your support team?

28. Difference between notification and delegate?

29. How will you create your own NSMutableArray class (This is a fav question of mine I ask this question so that I come to know how much you can think).

30. Read on how to upload an enterprise app and what are the necessary accounts or certificates required in this process. 

31.  Explain the iOS architecture OR explain the iphone OS architecture? 

32.  Your app is present in a jail break device so how will you make sure that the attacker does not get to sniff in plist files, User defaults or sqlite database present in the app sandbox?

So this was related with iOS development related questions few of my personal favorite are given below

1.   Find the factorial of a number without using any for, while, do-while or go-to?

2.   How will you multiply two numbers without using any arithmetic operator and math library?

3.  What happens if I make a web service call in the app did finish loading method and give the timeout interval as 20 minutes? Note: I am making a synchronous call here

4.   Difference between agile and waterfall model?

5.   Explain PGP i.e pretty good privacy and how does it work?

6.   Difference between encryption, cryptography and hashing?

7.   Difference between final and const (something out of objective C)

8.   Assuming I have an array filled with numbers from 1 to 6000 in this array at a given point there is a number that is duplicate, tell me the optimum solution to find that number using a single loop.

9.   Why objective C is called as a runtime language? (Pretty Basic :P )

10.   What is the difference between deep copy and shallow copy? And how will you implement this in objective C

11.   What is the meaning of HTTP and what does it do and why is HTTPS secure than HTTP?

from iPhoneradix..