2000+ iOS Interview Questions And Answers: Your Path to Success

8 min readJun 2, 2023

“Welcome to ‘2000+ iOS Interview Questions and Answers: Your Path to Success.’ I’m Ganesh Raju Galla, and I have meticulously gathered an extensive collection of over 2000+ iOS interview questions and their comprehensive answers. Whether you are a seasoned iOS developer looking to brush up on your skills or a job seeker preparing for interviews, this series of articles is designed to be your ultimate resource.

In the initial phase, the questions in this series will focus on Objective-C, covering a wide range of topics and scenarios commonly encountered during iOS interviews. However, as we progress, I will gradually transition to including questions based on Swift and SwiftUI, ensuring that you stay up to date with the latest technologies and frameworks in iOS development.

Every week, I will be releasing a new post featuring 50 carefully curated questions and their corresponding answers. The first 600 questions in this series will focus on objective-type questions, covering a wide range of topics and scenarios commonly encountered during iOS interviews.

So, fasten your seatbelt, as we embark on a journey that will unlock the secrets of iOS interview success. Let’s dive into the first set of 50 objective-type questions and answers, laying a solid foundation for your path to success in the dynamic world of iOS development.”

Please note that the revised introduction mentions the initial focus on Objective-C questions and the gradual transition to Swift and SwiftUI questions in the future.

NOTE: I have highlighted the answers in bold text. This distinctive formatting will help you easily spot the answers while reading the article.

⭐️ ① Written test questions-Grammar

1. The method corresponding to alloc is: [single-choice question]

A. alloc
B. dealloc
C. release
D. autorelease

2. The method corresponding to retain is: [single-choice question]

A. alloc
B. dealloc
C. release/autorelease
D. copy

3. The role of @property is to declare properties and their characteristics?: [single-choice question]

A. correct
B. wrong

4. The role of @synthesize is to automatically generate accessor (getter/setter) methods for attributes?: [Single-choice question]

A. correct
B. wrong

5. When is the dealloc method of an object called: [single-choice question]

A. The reference count (retuanCount) is reduced to -1
B. The reference count (retuanCount) is reduced to 1
C. The reference count (retuanCount) is reduced to 2
D. The reference count (retuanCount) is reduced to 0

6. Categories (categoryes) can be added to an existing class: [single-choice question]

A. Method
B. Attributes
C. action
D. agreement

7. Extensions can add [multiple choice questions] to the current class

A. action
B. Method
C. attributes
D. agreement

8. Protocols can be divided into two types, among which the protocol declared with which keyword may not be implemented: [single-choice question]

A. @optional
B. @required
C. @none
D. @userful

9. That class is the root class that most Objective-C classes inherit from, and it has no parent class [single-choice question]

A. NSNull
B. NS Interger
C. NSString
D. NSObject

10. The role of the agent ( delegate ) is to make one object implement the method of another object? [Judgment]

A. correct
B. wrong

11. `autorelease`The function is: [multiple choice]

A. Put the object into the autorelease pool
B. Decrease the reference count of the object by 1
C. Delay calling the release method
D. Immediately call the release method

12. `-(void) setName: (Nsstring) NewName{ self.name = NewName}`: The result of being called is: [Single-choice question]

A. Set the value of the name attribute
B. Program infinite loop
C. Get the value of the name attribute
D. Copy the value of the name attribute

13. `KVC` The common attribute accessor methods in China are those two: [Multiple choice]

A. valueForKey:
B. setValue:forKey:
C. getValueForKey:
D. SetValue:

14. Keywords `nil`are expressed in Objective-C: [single choice]

A. An empty object
B. A null pointer
C, a null character
D. A null byte

15. The difference between `#import`and `#include` is: `#import` Can you avoid the file being cited multiple times?: [Judgment]

A. correct
B. wrong

16. Does Objective-C support operator overloading: [Judgment]

A. correct
B. wrong

17. Can a private method be declared in a header file in Objective-C: [Judgment]

A. can
B. No

Objective-C Keyword Description

Objective-C Keyword Description
@private The scope of action can only be within its own class
@protected The scope of action is within its own class and subclasses that inherit from itself. If nothing is written, this property is the default.
@public Largest range of action, anywhere
@package will not be exported externally, so any class that tries to access these member variables outside the framework will get a linkage error as a result.

18. In Objective-C, the member variables of a class are declared by default as: [single choice]

A. @private The scope of action can only be within its own class
B. @protected The scope of action is within its own class and subclasses that inherit from itself. If nothing is written, this property is the default.
C. @public Largest range of action, anywhere.
D. @package will not be exported externally, so any class that tries to access these member variables outside the framework will get a linkage error as a result.

19. Regarding exception handling in Objective-C++, the following statement is most correct: [Single-choice question]

A. Objective-C does not support exception handling
B. In Objective-C++, the exception handling of Objective-C can catch the exception of C++
C. In Objective-C++, Objective-C exceptions cannot catch C++ exceptions
D. In Objective-C++, the exception handling of Objective-C and C++ can catch exceptions from each other

20. In the method of the object `dealloc`, `[super dealloc]`the correct statement about: grammar is: [single-choice question]

A. [super dealloc];
B. [super dealloc]; should be placed in the first line of the dealloc method
C. [super dealloc]; should be placed in the last line in the dealloc method
D. [super dealloc]; The location doesn’t matter, as long as it is in the dealloc method

21. The following about the method: `[[[object method1]method2] method3:[objectmethod4]];`the order of method calls in: [single-choice question]

A. 1 2 3 4
B. 1 2 4 3
C. 4 1 2 3
D. 4 3 2 1

22. In ARC `(Automatic Reference Counting)`mode, the following method is not disabled: [Single-choice question]

A. retain
B. copy
C. release
D. autorelease

23. Which of the following objects cannot `initWithContentsOfFile` be constructed by calling methods: [single-choice question]

A. NSString
B. NSXMLParser
C. NS Dicttionary
D. NSData

24. Which of the following keywords will add one to the reference count of the referenced object `(retainCount)`: [multiple choice]

A. alloc
B. init
C. retain
D. copy

25. In the file with the extension of .mm, what codes can be included: [multiple choice]

A.C
B. Objective-C
C. C++
D. Swift

26. Which of the following classes use the singleton `(Singletion)`pattern: [multiple choice]

A. File Manager
B. Notification Center
C. Application
D. Device

27. Among the following data types, those that can be directly put into `NSArray`the array are: [multiple choice]

A. BOOL
B. NSInteger
C. NSString
D. NSArray

28(enumerate). The advantages of the quick comparative access of Objective-C cycle , the following statement is correct: [multiple choice]

A. It is more efficient to use fast enumeration
B. The syntax is more concise
C. It is safer to use
D. More data types in the workplace

29. OC contains one custom header file that should be used: [single choice]

A. #include
B. #include<>
C. #import “”
D. #import<>

30.implemented protocol Which keyword statement must be used in the method: [single-choice question]

A. @property
B. @interface
C. @required
D. @protocol

31. Declare a method: provide an array of Student objects according to ascending order the judgment conditions of the student number: [single-choice question]

A. — (NScomparisonResult)compareWithNumberForAscendSort:(Student)otherStudent
B. — (NSinteger)compareWithNumberForAscendSort:(Student)otherStudent
C. — (BOOL) compareWithNumberForAscendSort:(Student) otherStudent
D. — (int) compareWithNumberForAscendSort:(Student) otherStudent

32. If the instance variable of a class in OC grammar Can only be accessed by this class and its subclasses requires which of the following modifiers: [single-choice question]

A. @public
B. @private
C. @protected
D. @friendly

33. The incorrect description of the collection is: [single-choice question]

A. All collections can add elements.
B. Collections are divided into mutable collections and immutable collections.
C. Array, dictionary and NSSet store data in different ways.
D. All collections can save id type data.

34. `NSDictionary *dict = [NSDictionary dictionaryWithObject:@"a value" forKey:@"aKey"];` NSLog(@”%@”,[dict objectForKey:@“aKey”]);[dict release]; What to output:[single-choice question]

A. a value Create a command line project on MacOS and set the non-ARC project to output a value
B. akey: a value
C. Crash information In the iOS project, setting a non-ARC project will crash
D. a vlaue : akey

35. To output a string to the OC console, you should use: [single-choice question]

A. NSLog()
B. Printf()
C. NSPrintf()
D. scanf()

36. The method named print:: has several incoming parameters: [single choice]

A, 0
B.1
C.2
D.3

37. Which of the following options `@synthesize`is used in conjunction with: [Single-choice question]

A. @end
B. @interface
C. @implementation
D. @property

38. In Objective-C, the root class of all classes is: [single choice]

A. NSObject
B. NSNull
C. NSCoding
D. UIView

39. Use OC language to implement “This is Objective-C program.” The correct one is: [single-choice question]

A. NSLog(@“%s”, This is Objective-C program.);
B. NSLog(@“%@”,This is Objective-C program.);
C. NSLog(@“This is Objective-C program.”,%@);
D. D. NSLog(@“This is Objective-C program.”,%@);

40. Agreement and commission The incorrect description is: [single-choice question]

A. Delegation is a design pattern of iOS
B. The methods in the protocol must be implemented by default
C. The class accepts multiple protocols. These protocols are written in <> behind the parent class, and multiple protocols are separated by “.”
D. Define the protocol using the @protocol keyword

41. The protocol incorrect description is: [single-choice question]

A. Agreements are divided into formal and informal agreements.
B. @required can be used when the class that requires the confirmation protocol must implement the method in the protocol.
C. A protocol can be confirmed by multiple classes.
D. The method declared in the protocol defaults to @optional.

42. In the following kind description of the concept, the error is: [single-choice question]

A. A class is an implementation of an abstract data type
B. A class is a unified description under several pairs of common behaviors
C. A class is a template for creating objects
D. A class is a structure type in C language

43. In Objective-C, which of the following options are The correct way to declare attributes : [single choice]

A. @property(nonatomic,retain) NSString *myString;
B. @property(nonatomic,assign) NSString *myString;
C. @property(nonatomic,assign) Int myNumber;
D. @property(nonatomic,retain) Int myNumber;

44. `NSString *name= [[NSString alloc]initWithString:@"Hello"]; NSLog(@"%d",[name retainCount]);`What is the output of the above code: [single choice]

A. -1
B.0
C.1
D.2

45. What will not immediately change the reference counter is: [single-choice question]

A. release
B. alloc
C. autorelease
D. retain

46. The best statement in OC entrust is: [single choice]

A. retain
B. assign
C. copy
D. readonly

47. After which of the following operations do you need to use release: [single-choice question]

A. delegate
B. assign
C. retain
D. dealloc

48(kind). The interface keywords in OC statement are: [single choice]

A. @import
B. @interface
C. @implemention
D. @protocol

49.-(id)setName:(NSString )name:(NSString )sex Age:(Int)age The method name is: [Single-choice question]

A. -(id)setName:(NSString *)name:(NSString *)setAge:(Int)age
B. setName:name:sex age:age
C. setName::age:
D. setName:name:age:

50. The code to replace @”2C Youth” with @”employed youth” is: [single-choice question]

A. [@“2C Youth” stringByAppendingOfString:@“2B” withString:@“intentionally”];
B. NSRange range = {0,2}; [@“2C Youth” stringByReplacingCharacterInRange:rangWithString:@“promising”];
C. NSRange range = {1,2}; [@“2C Youth” stringByReplacingCharacterInRange:rangWithString:@“promising”];
D. [@“2C Youth” stringByReplacingOccurrencesOfString:@“intentionally” withString:@“2C”];

Where to go from here:
2000+ iOS Interview Questions And Answers: Part — 2

Stay tuned for more iOS interview questions and answers. I’ll be updating the post with additional content to provide you with a comprehensive resource for your interview preparation. Keep an eye out for future updates!

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