1. What is the latest version of Swift?
A) Swift 4.0
B) Swift 5.0
C) Swift 6.0
D) Swift 7.0
Answer: B) Swift 5.0
2. What is optionals in Swift?
A) A way to represent that a value might be absent
B) A type of function in Swift
C) Another name for Swift closures
D) A way to use Swift with Objective-C code
Answer: A) A way to represent that a value might be absent
3. What is a guard statement in Swift?
A) A way to check the validity of a statement before executing it
B) A way to define a new variable in Swift
C) A type of loop in Swift
D) A way to call a function in Swift
Answer: A) A way to check the validity of a statement before executing it
4. What is a closure in Swift?
A) A way to represent a function without a name
B) A way to declare a new class in Swift
C) A way to store information in Swift
D) A type of error in Swift
Answer: A) A way to represent a function without a name
5. What is the use of a weak reference in Swift?
A) To avoid reference cycles
B) To ensure that a reference is strong
C) To define a new variable in Swift
D) To avoid memory leaks
Answer: A) To avoid reference cycles
6. What is a string interpolation in Swift?
A) A way to insert values into a string
B) A way to copy a string
C) A way to define a new string in Swift
D) A type of Swift loop
Answer: A) A way to insert values into a string
7. What is the use of guard let in Swift?
A) To unwrap an optional value
B) To define a new variable in Swift
C) To check the validity of a statement before executing it
D) To create a new array in Swift
Answer: A) To unwrap an optional value
8. What is the use of the defer keyword in Swift?
A) To delay the execution of a statement until the end of the current scope
B) To call a function in Swift
C) To define a new variable in Swift
D) To create a new class in Swift
Answer: A) To delay the execution of a statement until the end of the current scope
9. What is the difference between struct and class in Swift?
A) Structs are value types, while classes are reference types
B) Structs and classes cannot be used interchangeably
C) Structs are used for UI elements, while classes are used for data processing
D) Structs are immutable, while classes are mutable
Answer: A) Structs are value types, while classes are reference types
10. What is the use of the @escaping keyword in Swift?
A) To indicate that a closure might be called after a function has returned
B) To indicate that a function is throwing an error
C) To indicate that a variable is a reference type
D) To indicate that a function is generic
Answer: A) To indicate that a closure might be called after a function has returned
11. What is property observers in Swift?
A) A way to observe changes to a property’s value
B) A type of Swift loop
C) A way to declare a new property in Swift
D) Another name for Swift closures
Answer: A) A way to observe changes to a property’s value
12. What is the use of the @IBAction keyword in Swift?
A) To indicate that a function is being used as an action in an interface control
B) To indicate that a function is generic
C) To indicate that a variable is a reference type
D) To indicate that a function is throwing an error
Answer: A) To indicate that a function is being used as an action in an interface control
13. What is the difference between a force unwrap and a safe unwrap in Swift?
A) A force unwrap will crash if the value is nil, while a safe unwrap will not
B) A safe unwrap will crash if the value is nil, while a force unwrap will not
C) There is no difference between the two
D) A force unwrap and a safe unwrap can only be used with different types of variables
Answer: A) A force unwrap will crash if the value is nil, while a safe unwrap will not
14. What is the use of the @objc keyword in Swift?
A) To make a Swift function or variable accessible to Objective-C code
B) To declare a new class in Swift
C) To define a new variable in Swift
D) To create a new array in Swift
Answer: A) To make a Swift function or variable accessible to Objective-C code
15. What is the use of the didSet keyword in Swift?
A) To run a code block when a property’s value is set
B) To run a code block when a property’s value is accessed
C) To declare a new property in Swift
D) Another name for Swift closures
Answer: A) To run a code block when a property’s value is set
16. What is the difference between a protocol and a delegate in Swift?
A) A protocol defines a set of rules, while a delegate is an implementation of those rules
B) A protocol and a delegate are the same thing
C) A protocol is a way to store information, while a delegate is a way to access it
D) A protocol is immutable, while a delegate is mutable
Answer: A) A protocol defines a set of rules, while a delegate is an implementation of those rules
17. What is the use of the where keyword in Swift?
A) To apply a condition to a generic type or function
B) To define a new class in Swift
C) To declare a new variable in Swift
D) To create a new array in Swift
Answer: A) To apply a condition to a generic type or function
18. What is the use of the @IBOutlet keyword in Swift?
A) To indicate that a property is linked to an interface element
B) To indicate that a function is throwing an error
C) To indicate that a variable is a reference type
D) To indicate that a function is being used as an action in an interface control
Answer: A) To indicate that a property is linked to an interface element
19. What is the use of the @discardableResult keyword in Swift?
A) To indicate that the result of a function can be discarded if not needed
B) To indicate that the function is throwing an error
C) To indicate that a variable is a reference type
D) To indicate that a function is generic
Answer: A) To indicate that the result of a function can be discarded if not needed
20. What is the use of the fatalError() function in Swift?
A) To crash the program intentionally
B) To check a condition before proceeding with a statement
C) To define a new function in Swift
D) To create a new class in Swift
Answer: A) To crash the program intentionally
21. What is the use of the removeFromSuperview() function in Swift?
A) To remove a view from its superview
B) To add a view to its superview
C) To define a new class in Swift
D) To create a new function in Swift
Answer: A) To remove a view from its superview
22. What is the use of the guard else statement in Swift?
A) To handle any failure case in code
B) To create a new variable in Swift
C) To define a new function in Swift
D) To create a new class in Swift
Answer: A) To handle any failure case in code
23. What is the use of the break keyword in Swift?
A) To exit a loop or switch statement
B) To continue to the next iteration of a loop
C) To define a new variable in Swift
D) To create a new array in Swift
Answer: A) To exit a loop or switch statement
24. What is the use of the continue keyword in Swift?
A) To jump to the next iteration of a loop
B) To exit a loop or switch statement
C) To define a new variable in Swift
D) To create a new array in Swift
Answer: A) To jump to the next iteration of a loop
25. What is the use of the @available keyword in Swift?
A) To indicate the minimum version of iOS that a function or variable can be used
B) To indicate that a function is being used as an action in an interface control
C) To define a new variable in Swift
D) To create a new class in Swift
Answer: A) To indicate the minimum version of iOS that a function or variable can be used
26. What is the difference between a class method and an instance method in Swift?
A) A class method can be called on the class itself, while an instance method must be called on an instance of the class
B) A class method and an instance method are the same thing
C) A class method is defined in a protocol, while an instance method is defined in a class
D) A class method is immutable, while an instance method is mutable
Answer: A) A class method can be called on the class itself, while an instance method must be called on an instance of the class
27. What is the use of the didSet and willSet keywords in Swift?
A) To run code when a property’s value is about to change or has just changed
B) To define a new variable in Swift
C) To call a function in Swift
D) To create a new class in Swift
Answer: A) To run code when a property’s value is about to change or has just changed
28. What is the use of the guard statement in Swift?
A) To check the validity of a statement before executing it
B) To define a new variable in Swift
C) To create a new class in Swift
D) To call a function in Swift
Answer: A) To check the validity of a statement before executing it
29. What is the use of the didSet keyword in Swift?
A) To run a code block when a property’s value is set
B) To run a code block when a property’s value is accessed
C) To declare a new property in Swift
D) Another name for Swift closures
Answer: A) To run a code block when a property’s value is set
30. What is the use of lazy properties in Swift?
A) To defer the initialization of a property until it is first accessed
B) To define a new variable in Swift
C) To create a new array in Swift
D) To call a function in Swift
Answer: A) To defer the initialization of a property until it is first accessed
31. What is the use of the extension keyword in Swift?
A) To add functionality to an existing class or struct
B) To define a new class in Swift
C) To create a new variable in Swift
D) To create a new function in Swift
Answer: A) To add functionality to an existing class or struct
32. What is the difference between a closure and a function in Swift?
A) A closure is an unnamed function that captures and stores a reference to any constants and variables from the context in which it is defined, while a function is a named, self-contained block of code that performs a specific task.
B) A closure can only be used once, while a function can be used multiple times.
C) A closure can only be defined within another function or method, while a function can be defined anywhere.
D) There is no difference between the two.
Answer: A) A closure is an unnamed function that captures and stores a reference to any constants and variables from the context in which it is defined, while a function is a named, self-contained block of code that performs a specific task.
33. What is the use of the inout keyword in Swift?
A) To pass a variable by reference
B) To pass a variable by value
C) To define a new variable in Swift
D) To create a new function in Swift
Answer: A) To pass a variable by reference
34. What is the use of the @escaping keyword in Swift?
A) To indicate that a closure might be called after a function returns
B) To indicate that a function is throwing an error
C) To indicate that a variable is a reference type
D) To indicate that a function is generic
Answer: A) To indicate that a closure might be called after a function returns
35. What is the use of the finally keyword in Swift?
A) To run a block of code after a try-catch block, regardless of whether an error was thrown or caught
B) To define a new variable in Swift
C) To create a new class in Swift
D) To call a function in Swift
Answer: A) To run a block of code after a try-catch block, regardless of whether an error was thrown or caught
36. What is the use of a lazy stored property in Swift?
A) To defer initialization of a property until it is first accessed
B) To run a code block when a property’s value is set
C) To check the validity of a statement before executing it
D) To declare a new variable in Swift
Answer: A) To defer initialization of a property until it is first accessed
37. What is a generic type in Swift?
A) A way to define a type that can work with any other type
B) A type of loop in Swift
C) A way to declare a new variable in Swift
D) A way to use Swift with Objective-C code
Answer: A) A way to define a type that can work with any other type
38. What is the use of the map function in Swift?
A) To transform each element of an array using a provided closure
B) To remove elements from an array that meet certain conditions
C) To add elements to an array at specific positions
D) To obtain a subset of an array based on certain criteria
Answer: A) To transform each element of an array using a provided closure
39. What is the difference between “as” and “as!” in Swift?
A) “as” is used to perform an optional upcast, while “as!” is used for a force upcast
B) “as” is used for a force upcast, while “as!” is used to perform an optional upcast
C) “as” and “as!” are interchangeable
D) There is no difference between the two
Answer: A) “as” is used to perform an optional upcast, while “as!” is used for a force upcast
40. What is the use of the didSet keyword in Swift?
A) To run a code block when a property’s value is set
B) To run a code block when a property’s value is accessed
C) To declare a new property in Swift
D) Another name for Swift closures
Answer: A) To run a code block when a property’s value is set
41. What is the use of the @escaping keyword in Swift?
A) To indicate that a closure might be called after a function returns
B) To indicate that a function is throwing an error
C) To indicate that a variable is a reference type
D) To indicate that a function is generic
Answer: A) To indicate that a closure might be called after a function returns
42. What is the use of the @objc keyword in Swift?
A) To make a Swift function or variable accessible to Objective-C code
B) To declare a new class in Swift
C) To define a new variable in Swift
D) To create a new array in Swift
Answer: A) To make a Swift function or variable accessible to Objective-C code
43. What is the difference between let and var in Swift?
A) Let is used to declare a constant, while var is used to declare a variable.
B) Let can only be used with struct, while var can only be used with classes
C) There is no difference between the two
D) Let is used with classes, while var is used with structs
Answer: A) Let is used to declare a constant, while var is used to declare a variable.
44. What is the use of the guard statement in Swift?
A) To check the validity of a statement before executing it
B) To define a new variable in Swift
C) To create a new class in Swift
D) To call a function in Swift
Answer: A) To check the validity of a statement before executing it
45. What is the use of the implicitly unwrapped optional in Swift?
A) To declare an optional that is guaranteed to always contain a value
B) To declare a variable that is not optional
C) To define a new variable in Swift
D) To create a new array in Swift
Answer: A) To declare an optional that is guaranteed to always contain a value
46. What is a computed property in Swift?
A) A property whose value is calculated each time it is accessed
B) A property whose value is defined in the initializer and cannot be changed
C) A type of Swift loop
D) A way to store information in Swift
Answer: A) A property whose value is calculated each time it is accessed
47. What is the use of the @objcMembers keyword in Swift?
A) To automatically make all members of a class accessible to Objective-C code
B) To define a new class in Swift
C) To create a new variable in Swift
D) To create a new function in Swift
Answer: A) To automatically make all members of a class accessible to Objective-C code
48. What is the use of the ?? operator in Swift?
A) To provide a default value for an optional
B) To unwrap an optional
C) To check the validity of a statement before executing it
D) To define a new variable in Swift
Answer: A) To provide a default value for an optional
49. What is the use of the didSet keyword in Swift?
A) To run a code block when a property’s value is set
B) To run a code block when a property’s value is accessed
C) To declare a new property in Swift
D) Another name for Swift closures
Answer: A) To run a code block when a property’s value is set
50. What is the use of the optional chaining in Swift?
A) To safely unwrap an optional without the need for a force unwrap
B) To check the validity of a statement before executing it
C) To define a new variable in Swift
D) To create a new function in Swift
Answer: A) To safely unwrap an optional without the need for a force unwrap.
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