reduce combines a collection into one accumulated value.

Sum values with reduce

reduced_total.swift
let shipping = 
let prices = [12, 8, 5]
let subtotal = prices.reduce(0) { running, price in
    return running + price
}
let total = subtotal + shipping
let message = "total=\(total)"

print(message)
let shipping = 
let prices = [12, 8, 5]
let subtotal = prices.reduce(0) { running, price in
    return running + price
}
let total = subtotal + shipping
let message = "total=\(total)"

print(message)
let shipping = 
let prices = [12, 8, 5]
let subtotal = prices.reduce(0) { running, price in
    return running + price
}
let total = subtotal + shipping
let message = "total=\(total)"

print(message)
reduce The `reduce` method starts with an initial value, then folds each element into that running result.