Arrays
Arrays store values of a certain type in an ordered list. Examples:
let someInts = [1, 3, 5]
let someStrings = ["Hello", "Planet", "Earth"]
let someArraysOfInts = [[1, 2], [10, 20]]
print(someInts[0]) // 1
print(someStrings[2]) // Earth
print(someArraysOfInts[1]) // [10, 20]
- Mutability
- Type
- Arrays that allow any element type
- Iteration and manipulation
- See also
- Further reading
Mutability
Arrays defined with var are mutable:
var someStrings = ["Hello", "Planet", "Earth"]
someStrings.append("Neptune")
someStrings.remove(at: 2)
print(someStrings) // ["Hello", "Planet", "Neptune"]
Type
The type of an array can be determined without type annotations:
let someInts = [1, 3, 5] // Inferred to be type [Int]
let someStrings = ["Hello", "Planet", "Earth"] // Inferred to be [String]
But the type can also be explicitly declared:
let someInts: [Int] = [1, 3, 5]
let someStrings: [String] = ["Hello", "Planet", "Earth"]
And explicit types are required for empty arrays, because the type cannot be inferred:
let someStrings: [String] = []
let someInts = [Int]()
Arrays that allow any element type
Arrays can be declared to be of type [Any] in order to allow the insertion of any type of element:
var myArray1: [Any] = [1, 2, 3]
myArray1.append("Moon")
print(myArray1) // [1, 2, 3, "Moon"]
var myArray2 = [1, 2, 3]
myArray2.append("Moon") // ❌ Error: Unexpected type
Iteration and manipulation
Arrays can be iterated over using for-in and forEach. They can be manipulated using map, flatMap, reduce, and sorted.
