how to count specific items in array in swift

Question

Let's say i have array of any object below , I'm looking for a way to count items in the array as following:

var OSes = ["iOS", "Android", "Android","Android","Windows Phone", 25]

Is there a short way for swift to do something like this below ?

Oses.count["Android"]   // 3 

Answer 1

A fast, compact and elegant way to do it is by using the reduce method:

let count = OSes.reduce(0) { $1 == "Android" ? $0 + 1 : $0 }

It's more compact than a for loop, and faster than a filter, because it doesn't generate a new array.

The reduce method takes an initial value, 0 in our case, and a closure, applied to each element of the array.

The closure takes 2 parameters:

• the value at the previous iteration (or the initial value, 0 in our case)
• the array element for the current iteration

The value returned by the closure is used as the first parameter in the next iteration, or as the return value of the reduce method when the last element has been processed

The closure simply checks if the current element is Android:

• if not, it returns the aggregate value (the first parameter passed to the closure)
• if yes, it returns that number plus one

Answer 2

It's pretty simple with .filter:

OSes.filter({$0 == "Android"}).count // 3