300 IOS Interview Questions

Interviews become unnerving at times. But, in spite of whatever one thinks about it, you still have to go through it in order to get the job to leverage your geniuses and earn the income to fulfil your life goals.

These 300 IOS Interview Questions covers most of the things you need to practice to keep interview nerves at bay and ace your IOS interview. It is recommended to you that in the process of preparation, go through this question and practice before each of your interviews to remind yourself of them.

Why IOS? 

At this point, I’m sure you’re pretty equipped to make a decision about your future job. But you want a reason to pursue? let’s imagine that you’ve decided mobile development is the future and considering IOS over ANDROID, but you just need solid points to choose between both.

Although it’s primarily about passion, it is also important to have good career opportunities and ios developer have one. Companies all over the world are looking for ios developer and due to higher demand, they pay much higher than the Android developer(depends upon experience). But if you see mobile is still on the rise and ios is one of two dominant operating systems in that field.

Well, It’s easy for a newbie to learn IOS than Android. In IOS with all the restrictions making sure you’re much less likely to go off track while developing. one of the most important things is there will be fewer updates to make since there are a limited amount of Apple devices so you’ll be spending less time updating and more time on making it the best app form the rest.

So now you are clear about becoming an ios developer and for that, you need to crack interview to get a job and these 300 hand curated ios interview question will help you ace in your interview

300 IOS Interview Questions

1. How could you setup Live Rendering?
2. What is the difference between Synchronous & Asynchronous task?
3. Explain Compilation Conditions
4. What is made up of NSError object?
5. What is Enum or Enumerations?
6. What is the bounding box?
7. Why don’t we use strong for enum property in Objective-C?
8. What is @synthesize in Objective-C?
9. What is @dynamic in Objective-C?
10. Why do we use synchronized?
11. What is the difference strong, weaks, read only and copy?
12. What is Dynamic Dispatch?
13. What’s Code Coverage?
14. What’s Completion Handler?
15. How to Prioritize Usability in Design ?
16. What’s the difference between the frame and the bounds?
17. What is Responder Chain ?
18. What is Regular expressions ?
19. What is Operator Overloading ?
20. What is TVMLKit?
21. What is Platform limitations of tvOS?
22. What is Functions?
23. What is ABI?
24. Why is design pattern very important ?
25. What is Singleton Pattern ?
26. What is Facade Design Pattern?
27. What is Decorator Design Pattern?
28. What is Adapter Pattern?
29. What is Observer Pattern?
30. What is Memento Pattern?
31. Explain MVC
32. Explain MVVM
33. How many different annotations available in Objective-C ?
34. What is JSON/PLIST limits ?
35. What is SQLite limits ?
36. What is Realm benefits ?
37. How many are there APIs for battery-efficient location tracking ?
38. What is the Swift main advantage ?
39. Explain generics in Swift ?
40. Explain lazy in Swift ?
41. Explain what is defer ?
42. How to pass a variable as a reference ?
43. How to pass data between view controllers?
44. What is Concurrency ?
45. Grand Central Dispatch (GCD)
46. Readers-Writers
47. NSOperation — NSOperationQueue — NSBlockOperation
48. KVC — KVO
49. Please explain Swift’s pattern mat
50. ching techniques
51. Explain Guard statement
52. Please explain Method Swizzling in Swift
53. What is the difference Non-Escaping and Escaping Closures?
54. Explain [Week self] and [unowned self] ?
55. What is ARC ?
56. Explain #keyPath() ?
57. What is iOS 11 SDK Features for Developers?
58. What makes React Native special for iOS?
59. What is NSFetchRequest?Explain NSPersistentContainer
60. Explain NSFetchedResultsController
61. What is the three major debugging improvements in Xcode 8?
62. What is the Test Driven Development of three simple rules?
63. Please explain final keyword into the class?
64. What does Yak Shaving mean?
65. What is the difference open & public access level?
66. What is the difference fileprivate, private and public private(set) access level ?
67. What is Internal access ?
68. What is the difference between BDD and TDD?
69. Please explain “Arrange-Act-Assert”
70. What is the benefit of writing tests in iOS apps?
71. What is five essential practical guidelines to improve your typographic quality of mobile product designs?
72. Explain Forced Unwrapping
73. How to educate app with Context?
74. What is bitcode ?
75. Explain Swift Standard Library Protocol ?
76. What is the difference SVN and Git ?
77. What is the difference CollectionViews & TableViews?
78. What is Alamofire doing?
79. REST, HTTP, JSON — What’s that?
80. What problems does delegation solve?
81. What is the major purposes of Frameworks?
82. Explain Swift Package Manager
83. What is the difference between a delegate and an NSNotification?
84. Explain SiriKit Limitations
85. Why do we use a delegate pattern to be notified of the text field’s events?
86. How is an inout parameter different from a regular parameter?
87. Explain View Controller Lifecycle events order?
88. What is the difference between LLVM and Clang?
89. What is Class ?
90. What is Object?
91. What is interface?
92. When and why do we use an object as opposed to a struct?
93. What is UIStackView?
94. What are the states of an iOS App?
95. What are the most important application delegate methods a developer should handle?
96. What is the difference between property and instance variable?
97. How can we add UIKit for Swift Package Manager?Explain the difference between SDK and Framework
98. What is Downcasting?
99. Explain Labeled Statements
100. What is Nil Coalescing & Ternary Operator?
101. What kind of JSONSerialization have ReadingOptions?
102. How can you prevent a user from doing said action more than once on their device?
103. What is DispatchGroup?
104. What is RGR ( Red — Green — Refactor)?
105. Where do we use Dependency Injection ?
106. Please explain types of notifications.
107. When is a good time for dependency injection in our projects?
108. What kind of order functions can we use on collection types ?
109. What allows you to combine your commits ?
110. What is the difference ANY and ANYOBJECT ?
111. Please explain SOAP and REST Basics differences ?
112. What is your favorite Visualize Chart library?
113. What is the difference Filter and Map Function?
114. What is CoreData ?
115. Could you explain Associatedtype ?
116. Which git command saves your code without making a commit ?
117. Explain Priority Inversion and Priority Inheritance.
118. What is Hashable?
119. When do you use optional chaining vs. if let or guard?
120. How many different ways to pass data in Swift?
121. How do you follow up clean code for this project?
122. Explain to using Class and Inheritance benefits
123. What’s the difference optional between nil and . None?
124. What is GraphQL?
125. Explain Common features of Protocols & superclasses
126. What is Continuous Integration?
127. What is the difference Delegates and Callbacks?
128. Explain Linked List
129. Do you know Back End development?
130. Explain AutoLayout
131. What is the disadvantage to hard-coding log statements ?
132. What is Pointer ?
133. Explain Core ML Pros and Cons
134. What is pair programming?
135. Explain blocks
136. What is Keychain ?
137. What is the biggest changes in UserNotifications ?
138. Explain the difference between atomic and nonatomic synthesized properties
139. Why do we use availability attributes ?
140. How could we get device token ?
141. What is Encapsulation ?
142. What is big-o notation ?
143. What Is Dependency Management?
144. What is UML Class Diagrams?
145. Explain throw
146. What is Protocol Extensions?
147. What is three triggers for a local notification ?
148. Explain Selectors in ObjC
149. What is Remote Notifications attacment’s limits ?
150. Explain Data Structures
151. Explain CodingKey Protocol
152. Explain IGListKit
153. What is URLSession?
154. How do we download images?
155. How does TestFlight make a difference?
156. What is SnapKit or Masonry make a difference from Auto layout?
157. Explain IteratorProtocol
158. Explain differences between WKWebView and UIWebView
159. Explain XLIFF Pros and Cons
160. What is difference Layout Margins and Directional Layout Margins ?
161. What is Sequence protocol ?
162. What is OAuth ?
163. What is offset ?
164. Explain rethrows keyword
165. Explain @objc inference
166. What is Safe area ?
167. Explain Viper Architecture
168. Explain Content offset
169. Explain Queues
170. Explain @objcMembers inference
171. What’s new with Xcode Server ?
172. Explain type inference
173. What is the difference between Array vs NSArray ?
174. What is NSLayoutAnchor ?
175. What is themutating keyword ?
176. What is snapshot testing ?
177. What is circular dependencies ?
178. What’s the difference between MKAnnotation and MKPointAnnotation?
179. What is DTO ?
180. Explain Main Thread Checker
181. What is the difference Stack and Heap ?
182. Explain VIP ( Clean-Swift) Architecture
183. Explain UIBezierPath
184. Explain Dependency Injection Container
185. Explain ObjectMapper for parsing JSON data
186. Explain CAShapeLayer
187. Explain Get Request Steps
188. Explain coordinate systems in views
189. Explain Encoding, Decoding and Serialization, Deserialization
190. What is the purpose of using IBAction and IBOutlet ?
191. Explain AlamoFire Benefits
192. Explain Semaphore in iOS
193. What is LLDB?
194. Explain Tuples
195. Explain the difference between Generics and AnyObject in Swift
196. Explain Dependency Inversion Principle
197. What is Smoke Testing?
198. Explain how does UIEdgeInsetsMake work?
199. What is the meaning of id ?
200. What excites or interests you about making software?
201. Which version control systems are you familiar with?
202. Do you have experience working with projects on GitHub?
203. Do you contribute to any iOS open source projects on GitHub or a similar site?
204. Can you describe your workflow when you work on creating an iOS app?
205. Are you familiar with CocoaPods? Can you explain what they are and how they work?
206. In general, explain software licensing and how this applies to work we do.
207. Describe your general testing practices when building an iOS app.
208. How can apps support other languages, date formats and currencies?
209. What is Instruments and how is it useful?
210. Explain Handoff, and in general, how it allows iOS and Mac/web apps to communicate?
211. What technologies/services are contained inside of iCloud?
212. What is an iOS extension? Can you list a few examples of popular/common extensions?
213. What is HealthKit?
214. What is HomeKit?
215. What is Apple Pay? Could you describe a way we could use it in our applications?
216. Explain application sandboxing.
217. What is VoiceOver? Explain some of the accessibility features included in iOS and how developers can utilize them.
218. How does application multitasking work on iOS?
219. What features does Game Center offer for iOS games?
220. What are iBeacons?
221. What is Cocoa/Cocoa Touch?
222. Explain in general, what Core Audio, Core Data, and Core Location are, and how they help iOS apps.
223. Describe the role of SpriteKit and SceneKit.
224. What is Metal?
225. What is the responder chain? How does it work?
226. What are the different actions that buttons and other controls can respond to?
227. What is the role of the application delegate?
228. Explain NSUserDefaults. How would you serialize an array to disk?
229. How would you store user’s credentials?
230. Explain Keychain Services.
231. Why are caching and compression important on mobile devices?
232. Explain ~/Documents, ~/Library, ~/tmp. What directory is ~ on iOS?
233. How does AirPlay work? How would you use it (programmatically) to enhance the utility and presentation of an app?
234. Give a brief overview of what sensors, IO and communication methods (Wifi, telephony, etc) are available on iOS. How can you make use of these?
235. What are the hardware performance differences among the iPad 2 / iPad mini 1-3, iPad Retina, iPad Air 2, iPhone 5, 5s, 6, and 6+.
236. What do these constraints mean for performance intensive apps?
237. What does Cocoa Touch include and not include?
238. Why do Cocoa Touch classes start with two capital letters?
239. What is Swift, what is Objective-C and how do they relate and compare?
240. Explain why optionals are useful in Swift.
241. Explain NSError and how it works (or doesn’t) in Swift.
242. How does instancetype work and how is it useful?
243. When is let appropriate in Swift? var?
244. Why and where is the map function useful.
245. How do you track down bugs? What are your tools of choice?
246. You found a bug in Cocoa. What do you do?
247. There is a regression in a new distributed version of our app causing crashes. How do you mitigate it? How will you prevent new bugs
248. from reaching customers?
249. How are Objective-C classes implemented? Describe how the Objective-C runtime is implemented.
250. What security does iOS offer to protect customers and privileged information?
251. Our app downloads data and displays it immediately. In accordance with MVC where is the best place to perform the download?
252. How does MVC influence the design of a codebase?
253. What methods are part of the controller life-cycle? The view life-cycle
254. What design patterns does iOS make use of? What design patterns do you use in your codebase?
255. What queues does iOS provide and how can you best utilize them?
256. Give a brief description of how UIScrollView is implemented. How does it operate with gesture recognizers, multiple touches and the run loops?
257. What API would you add or improve on iOS?
258. What is the screen resolution of the iPhone 5, 6, 6+. and iPad Air 2?
259. What units is the resolution measured in?
260. Explain the purpose of Interface Builder, what is a NIB file?
261. What image filetype should iOS UI assets be saved in?
262. Describe some differences between a Storyboard and a standard NIB file.
263. What is the device status bar? How tall is it in points? Is it opaque or transparent? What does it do during a phone call or navigation?
264. What is a navigation bar? Can you show me an Apple app on your phone that uses a navigation bar?
265. What is a tab bar? What is a toolbar? Compare and contrast them.
266. What is a table view? What is a collection view?
267. Describe when a popover is most appropriate.
268. What is a split-view controller?
269. What sort of content would be appropriate to place in a picker view?
270. When are a label, text field and text view appropriate?
271. What does a segmented control do?
272. What is a modal view?
273. What kind of notifications does iOS offer?
274. What is an iOS app icon? Describe it as best as you can.
275. What is the smallest size an app icon could be? What’s the largest size it could be?
276. Can an app icon contain any transparency?
277. How does a Newsstand icon differ from a regular app icon?
278. Explain a launch image.
279. Describe the purpose of Auto Layout, and in general, how it works.
280. Describe the role of animation in design of software.
281. Describe the role of interactivity and feedback when designing software.
282. What are some differences to take into account when building an iPhone app vs an iPad app?
283. Describe the importance and role of prototyping when working on an app design.
284. How do In-App Purchases work? What can be purchased with IAP?
285. Have you ever submitted an app to the App Store? Can you explain the general process?
286. What is iTunes Connect?
287. What is a provisioning profile?
288. What is an App ID?
289. What are the differences between Development and Production iOS signing certificates?
290. How is TestFlight used? How were UUIDs used in ad-hoc app distribution?
291. When do purchase receipts need to be verified?
292. What is required to display iAds?
293. What’s a cool thing you’ve coded recently? What’s something you’ve built that you’re proud of?
294. What are some things you like about the developer tools you use?
295. Who are some of your favourite independent Mac or iOS developers?
296. Do you have any pet projects? What kind?
297. What would you change about Xcode?
298. What is your favourite iOS API?
299. What are your favourite ways to investigate new technology?
300. Why are dictionaries called dictionaries? Why not hash tables or hash maps?

Closing Notes

Great!!, finally you made it to the end of the article… Wish you all the best for your IOS Interview! We hope now you can crack any tough nut, Practice these question by taking a MOCK INTERVIEW FOR FREE