Basic Types and Collections

Swift's fundamental types are Int, Double, Float, Bool, String, and Character. The standard library also provides Array, Dictionary, and Set as generic collection types. Arrays are ordered collections, dictionaries map keys to values, and sets store unique unordered values. All three are value types — assigning a collection to a new variable creates a copy. Swift provides type-safe collections through generics: [Int] is an array of integers, [String: Int] is a dictionary mapping strings to integers.

Example

// Arrays
var fruits: [String] = ["apple", "banana", "cherry"]
fruits.append("date")
fruits.insert("avocado", at: 0)
print(fruits.count)       // 5
print(fruits[1])          // banana

// Array operations
let doubled = fruits.map { $0.uppercased() }
let filtered = fruits.filter { $0.count > 5 }
let joined = fruits.joined(separator: ", ")

// Dictionaries
var scores: [String: Int] = ["Alice": 95, "Bob": 87]
scores["Charlie"] = 92
scores.updateValue(90, forKey: "Bob")

for (name, score) in scores {
    print("\(name): \(score)")
}

// Sets
var uniqueTags: Set<String> = ["swift", "ios", "mobile"]
uniqueTags.insert("apple")
let hasSwift = uniqueTags.contains("swift")

// Set operations
let a: Set = [1, 2, 3, 4]
let b: Set = [3, 4, 5, 6]
print(a.union(b))         // {1,2,3,4,5,6}
print(a.intersection(b))  // {3,4}

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