Is it possible to create custom queue types?

Yes, using OperationQueue and Operation.

import Foundation

class MyOperation: Operation {
    override func main() {
        if isCancelled { // Check for operation cancellation
            return
        }
        print("Executing MyOperation")
        // Main logic of the operation
    }
}

let customQueue = OperationQueue()
customQueue.maxConcurrentOperationCount = 2 // Limit on the number of concurrently executing operations

customQueue.addOperation(MyOperation())
customQueue.addOperation(MyOperation())
customQueue.addOperation(MyOperation())

// Wait for all operations in the queue to finish
// customQueue.waitUntilAllOperationsAreFinished()

OperationQueue manages the execution of Operation. You can configure properties such as the maximum number of operations that can run simultaneously. Operation represents a separate unit of work and can be added to the queue.