Returns the result of combining the elements of the sequence using the given closure.
- iOS 7.0+
- macOS 10.9+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
- Xcode 9.0+
The value to use as the initial accumulating value.
initialis passed to
nextthe first time the closure is executed.
A closure that combines an accumulating value and an element of the sequence into a new accumulating value, to be used in the next call of the
nextclosure or returned to the caller.
The final accumulated value. If the sequence has no elements, the result is
reduce(_: method to produce a single value from the elements of an entire sequence. For example, you can use this method on an array of numbers to find their sum or product.
next closure is called sequentially with an accumulating value initialized to
initial and each element of the sequence. This example shows how to find the sum of an array of numbers.
numbers is called, the following steps occur:
nextclosure is called with
0in this case—and the first element of
numbers, returning the sum:
The closure is called again repeatedly with the previous call’s return value and each element of the sequence.
When the sequence is exhausted, the last value returned from the closure is returned to the caller.
If the sequence has no elements,
next is never executed and
initial is the result of the call to
Complexity: O(n), where n is the length of the sequence.