subscript(_:)

Declaration

subscript(i: Int) -> Element { get nonmutating set }

Parameters

• i:

  The position of the element to access. i must be in the range 0..<count.

Overview

The following example uses the buffer pointer’s subscript to access and modify the elements of a mutable buffer pointing to the contiguous contents of an array:

var numbers = [1, 2, 3, 4, 5]
numbers.withUnsafeMutableBufferPointer { buffer in
    for i in stride(from: buffer.startIndex, to: buffer.endIndex - 1, by: 2) {
        let x = buffer[i]
        buffer[i + 1] = buffer[i]
        buffer[i] = x
    }
}
print(numbers)
// Prints "[2, 1, 4, 3, 5]"

Uninitialized memory cannot be initialized to a nontrivial type using this subscript. Instead, use an initializing method, such as initializeElement(at:to:)