MultipleHeavyAsynchronousCallBackTask

multipleHeavyAsynchronousCallBackTask.swift

func multipleHeavyAsynchronousCallBackTask(start: Int, end: Int, completionHandler: @escaping ([Int]) -> Void) {
        //1. Gets the array of numbers (A dummy heavy operation)
        HeavyOperationApi.shared.heavyNumberArray(from: start, to: end) { numbers in
            //2. Using the numbers array to fillter for Even number (A Dummy heavy operation)
            HeavyOperationApi.shared.heavyFilterEvenNumberFrom(arrayOf: numbers) { evenNumbers in
                // 3. Doing Random mapping of even numbers array (A Dummy Heavy operation)
                HeavyOperationApi.shared.heavyRandomMapping(arrayOf: evenNumbers) { number in
                    return number + 10000000
                } completion: { transformedNumbrs in
                    completionHandler(transformedNumbrs)
                }

            }
        }
    }


enum HeavyOperationApiError: LocalizedError {
    case reserveNumberError
}

class HeavyOperationApi {
    
    private let sleepTime: UInt64 = 10
    
    static let shared = HeavyOperationApi()
    
    private init() {}
  
    func heavyNumberArray(from: Int, to: Int, completion:  @escaping /*@Sendable*/ ([Int]) -> Void) {
        
        DispatchQueue.global(qos: .userInitiated).async {
            
            var number: [Int] = []
            for i in from...to {
                number.append(i)
            }
            
            completion(number)
        }
    }
    
    func heavyFilterEvenNumberFrom(arrayOf numbers: [Int], completion:  @escaping /*@Sendable*/ ([Int]) -> Void ) {
        
        DispatchQueue.global(qos: .userInitiated).async {
            completion(numbers.filter { number in
                number % 2 == 0
            })
        }
    }
    
    func heavyRandomMapping<T>(arrayOf numbers: [Int], transform: @escaping @Sendable (Int) -> T, completion:  @escaping @Sendable ([T]) -> Void) {
        
        DispatchQueue.global(qos: .userInitiated).async {
            completion(numbers.map { number in
                transform(number)
            })
        }
        
    }
}