ConcurrentPerformer

ConcurrentPerformer.swift

import Foundation

final class ConcurrentPerformer {
    
    func perform<T>(_ objects: [T], iterations: Int? = nil, action: ((T) -> ())) {
        if let iterations = iterations {
            customPerform(objects, iterations: iterations, action: action)
        } else {
            defaultPerform(objects, action: action)
        }
    }
    
    private func defaultPerform<T>(_ objects: [T], action: ((T) -> ())) {
        let array = objects as NSArray
        array.enumerateObjects(options: .concurrent) { obj, _, _  in
            if let obj = obj as? T {
                action(obj)
            }
        }
    }
    
    private func customPerform<T>(_ objects: [T], iterations: Int, action: ((T) -> ())) {
        let objectsPerIteration = Int(objects.count / iterations) + 1
        DispatchQueue.concurrentPerform(iterations: iterations) { index in
            for index in index * objectsPerIteration ..< (index + 1) * objectsPerIteration {
                guard index < objects.count else { continue }
                let object = objects[index]
                action(object)
            }
        }
    }
    
}