How to create Dependencies for NSOperationBlock in swift

DependencyNSOperationBlock.swift

let operationQueue = OperationQueue()

let op0 = BlockOperation()
op0.completionBlock = {
    print("op0 completionBlock")
}
op0.addExecutionBlock {
    print("op0 executionBlock #1")
}
op0.addExecutionBlock {
    print("op0 executionBlock #2")
}
op0.queuePriority = .veryHigh


let op1 = BlockOperation()
op1.addDependency(op0)
op1.completionBlock = {
    print("op1 completionBlock")
}
op1.addExecutionBlock {
    print("op1 executionBlock")
}


let op2 = BlockOperation()
op2.addDependency(op1)
op2.completionBlock = {
    print("op2 completionBlock")
}
op2.addExecutionBlock {
    print("op2 executionBlock")
}

operationQueue.addOperations([op0, op1, op2], waitUntilFinished: true)