MCQs on Collections | Swift

Swift collections—arrays, dictionaries, sets, and tuples—are fundamental for effective data management and manipulation. Dive into this well-structured chapter with MCQs tailored to sharpen your Swift programming skills.

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Topic 1: Arrays – Declaration, Operations, and Iteration

1. Which of the following correctly declares an empty array of integers in Swift?
   a) let numbers = Array<Int>()
   b) let numbers = [Int]
   c) let numbers: [Int] = []
   d) All of the above
2. How do you append a new element to an existing array?
   a) array.add(element)
   b) array.append(element)
   c) array.insert(element)
   d) array.addElement(element)
3. Which method removes the last element of an array in Swift?
   a) removeFirst()
   b) removeLast()
   c) pop()
   d) remove()
4. What does the following code output?swiftCopy codelet fruits = ["Apple", "Banana", "Cherry"] print(fruits[1]) a) Apple
   b) Banana
   c) Cherry
   d) Error
5. How can you iterate through all elements of an array?
   a) Using for element in array
   b) Using array.each
   c) Using while let element in array
   d) All of the above

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Topic 2: Dictionaries – Key-Value Pair Management

6. How do you declare an empty dictionary in Swift?
   a) let dict = [String: Int]()
   b) let dict = Dictionary<String, Int>()
   c) let dict: [String: Int] = [:]
   d) All of the above
7. What happens if you try to access a non-existent key in a dictionary?
   a) Error
   b) Returns nil
   c) Returns default value
   d) None of the above
8. Which method removes a key-value pair from a dictionary?
   a) remove(key:)
   b) deleteValue(forKey:)
   c) removeValue(forKey:)
   d) removeElement(key:)
9. How can you retrieve all keys from a dictionary?
   a) dict.keys
   b) dict.getKeys()
   c) dict.allKeys
   d) None of the above
10. Given the dictionary:swiftCopy codelet scores = ["Math": 90, "Science": 95] How can you update the value for key "Math" to 100?
    a) scores.updateValue(100, forKey: "Math")
    b) scores["Math"] = 100
    c) Both a and b
    d) None of the above

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Topic 3: Sets – Unique Elements and Membership

11. Which of the following declares a set of integers?
    a) var set: Set = [1, 2, 3]
    b) var set = Set<Int>()
    c) Both a and b
    d) None of the above
12. Which operation checks if a set contains an element?
    a) set.contains(element)
    b) set.has(element)
    c) set.includes(element)
    d) set.elementExists()
13. How do you combine two sets in Swift?
    a) set1.merge(set2)
    b) set1.formUnion(set2)
    c) set1.append(set2)
    d) set1.combine(set2)
14. Which operation returns elements that are common to two sets?
    a) union()
    b) intersection()
    c) difference()
    d) exclusive()
15. What does the following code return?swiftCopy codelet setA: Set = [1, 2, 3] let setB: Set = [3, 4, 5] setA.isSubset(of: setB) a) true
    b) false
    c) Error
    d) None of the above

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Topic 4: Tuples – Grouping Values

16. Which of the following correctly declares a tuple?
    a) let tuple = ("John", 25)
    b) let tuple: (String, Int)
    c) let tuple = (name: "John", age: 25)
    d) All of the above
17. How do you access the second element of a tuple?
    a) tuple[1]
    b) tuple.1
    c) tuple.second
    d) tuple["second"]
18. Can tuples have named elements?
    a) Yes, always
    b) No, never
    c) Yes, optionally
    d) None of the above
19. What is the output of the following code?swiftCopy codelet person = (name: "Alice", age: 30) print(person.name) a) Alice
    b) 30
    c) Error
    d) None of the above
20. Which operation creates a new tuple by combining two tuples?
    a) Using + operator
    b) Using tuple1.combine(tuple2)
    c) Using (tuple1, tuple2)
    d) None of the above

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Answers Table

QNo	Answer
1	d) All of the above
2	b) array.append(element)
3	b) removeLast()
4	b) Banana
5	a) Using for element in array
6	d) All of the above
7	b) Returns nil
8	c) removeValue(forKey:)
9	a) dict.keys
10	c) Both a and b
11	c) Both a and b
12	a) set.contains(element)
13	b) set1.formUnion(set2)
14	b) intersection()
15	b) false
16	d) All of the above
17	b) tuple.1
18	c) Yes, optionally
19	a) Alice
20	c) Using (tuple1, tuple2)