How do you sum all elements of an array?

let numbers = [1, 2, 3, 4, 5]  

// reduce method
let sumReduce = numbers.reduce(0, +)  

// for-in loop
var sumForIn = 0  
for number in numbers {  
    sumForIn += number  
}  

// Using forEach (less preferred for summing, but possible)
var sumForEach = 0  
numbers.forEach { number in  
    sumForEach += number  
}