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
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 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:
reduce(). +1
for case syntax to deal with count specific items in Array. Your method is more swifty.It's pretty simple with .filter:
OSes.filter({$0 == "Android"}).count // 3
reduce is more performant, but I prefer filter().count for readability.
Swift 5 with count(where:)
let countOfAndroid = OSes.count(where: { $0 == "Android" })
Swift 4 or less with filter(_:)
let countOfAndroid = OSes.filter({ $0 == "Android" }).count
count(where:) was briefly with us in Swift 5, but sadly it was removed because of conflicts with the type checking system.