Swift Collection Protocols

Swift Collection Protocols

Arrays, Sets and Dictionaries conform to Sequence and Collection, which provide common APIs like count and isEmpty.

---

Common APIs

Use count and isEmpty to check collection size.

Example

let arr = [1, 2, 3]
print(arr.count)
print(arr.isEmpty)
let s: Set<Int> = [1, 2, 3]
print(s.contains(2))
print(s.isEmpty)

This example shows shared operations exposed via collection protocols.

---

---

Indices

Use the indices property to iterate valid positions.

Example

let arr = [10, 20, 30]
for i in arr.indices {
  print("index: \(i), value: \(arr[i])")
}