FunctionSwift

stride(from:to:by:)

Returns a sequence from a starting value to, but not including, an end value, stepping by the specified amount.

``func stride<T>(from start: T, to end: T, by stride: T.Stride) -> StrideTo<T> where T : Strideable``

Parameters

start

The starting value to use for the sequence. If the sequence contains any values, the first one is `start`.

end

An end value to limit the sequence. `end` is never an element of the resulting sequence.

stride

The amount to step by with each iteration. A positive `stride` iterates upward; a negative `stride` iterates downward.

Returns

A sequence from `start` toward, but not including, `end`. Each value in the sequence steps by `stride`.

Overview

You can use this function to stride over values of any type that conforms to the `Strideable` protocol, such as integers or floating-point types. Starting with `start`, each successive value of the sequence adds `stride` until the next value would be equal to or beyond `end`.

``````for radians in stride(from: 0.0, to: .pi * 2, by: .pi / 2) {
let degrees = Int(radians * 180 / .pi)
}

You can use `stride(from:to:by:)` to create a sequence that strides upward or downward. Pass a negative value as `stride` to create a sequence from a higher start to a lower end:

``````for countdown in stride(from: 3, to: 0, by: -1) {
print("\(countdown)...")
}
// 3...
// 2...
// 1...``````

If you pass a value as `stride` that moves away from `end`, the sequence contains no values.

``````for x in stride(from: 0, to: 10, by: -1) {
print(x)
}
// Nothing is printed.``````