How to create NSOperationQueue

NSOperationQueue.swift

let operationQueue1 = OperationQueue.init()

let operation1 = BlockOperation.init()
operation1.addExecutionBlock {
    print("I am operation execution block injected in the operation1")
}

operationQueue1.addOperation(operation1)
operationQueue1.addOperation {
    print("I am operation execution block injected direct to queue by operation")
}