deda9

func createRxObservable() {
    let source: Observable<Int> = Observable.interval(1, scheduler: ConcurrentDispatchQueueScheduler.init(qos: DispatchQoS.background)).take(3)
        source
        .subscribe(onNext: { number in
            print("Second: ", number)
        }, onError: { _ in print("On Error") },
           onCompleted: { print("Complete") },
           onDisposed: nil)
}

deda9

func createRxObservable() {
    
    let source = Observable<Int>.from([1, 2, 3, 4, 6, 7])
    
    source
        .subscribe(onNext: { number in
            print("Current emitted number: ", number)
        }, onError: { _ in print("On Error") },
           onCompleted: { print("Complete") },
           onDisposed: nil)

deda9

func createRxObservable() {
    let source: Observable<Int>  = Observable.deferred {
        let source: Observable<Int> = Observable.create { observer in
            for i in 1...5 {
                observer.on(.next(i))
            }
            observer.on(.completed)
            return Disposables.create()
        }
        return source

deda9

func createRxObservable() {
    let source: Observable<Int> = Observable.create { observer in
        for i in 1...5 {
            observer.on(.next(i))
        }
        observer.on(.completed)
        return Disposables.create()
    }
    
    source

deda9

let group = DispatchGroup()
group.enter()

let dispatchQueue1 = DispatchQueue.init(label: "dispatchQueue")

dispatchQueue1.sync {
    for i in 0..<5 {
        print("DispatchQueue X ", i)
    }
    group.leave()

deda9

//With Different priority
let dispatchQueue1 = DispatchQueue(label: "Queue 1", qos: .userInteractive)
let dispatchQueue2 = DispatchQueue(label: "Queue 2", qos: .background)

dispatchQueue1.async {
    for i in 0..<5 {
        print("DispatchQueue X ", i)
    }
}

deda9

let dispatchQueue = DispatchQueue(label: "Background", attributes: .concurrent)
dispatchQueue.async {
    for i in 0..<5 {
        print("DispatchQueue X ", i)
    }
}

dispatchQueue.async {
    for i in 5..<10 {
        print("DispatchQueue Y ", i)

deda9

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")

deda9

let operationQueue = OperationQueue()

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

deda9

enum OperationState: Int {
    case ready
    case executing
    case finished
}

class CustomOperationBlock: Operation{
    
   private var state: OperationState!