olbrichj

import Foundation

class HelloWorldOperation: GroupOperation {
    override init() {
        super.init()
        
        let op = TextOperation(text: "Hello")
        let op2 = TextOperation(text: "World")

        op2.addDependency(op)

olbrichj

import Foundation

class OperationObserver: NSObject {
    init(operation: AsyncOperation) {
        super.init()
        operation.addObserver(self, forKeyPath: "finished", options: .new, context: nil)
    }
    
    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        guard let key = keyPath else {

olbrichj

let op1 = Operation1()
let op2 = Operation2()


let adapter = BlockOperation() { [unowned op1, unowned op2] in
    op2.data = op1.data
}

adapter.addDependency(op1)
op2.addDependency(adapter)

olbrichj

class GroupOperation: AsyncOperation {
    let queue = OperationQueue()
    var operations: [AsyncOperation] = []
    var errors: [Error] = []
    
    override func execute() {
        print("group started")
        queue.addOperations(operations, waitUntilFinished: true)
        print("group done")
    }

olbrichj

import Foundation

class UIOperation: AsyncOperation {
    let viewController: UIViewcontroller!
  
    override func execute() {
        let alert = UIAlertController(title: "My Alert", message: @"This is an alert.", preferredStyle: .alert) 
        alert.addAction(UIAlertAction(title: "OK", style: .`default`, handler: { _ in 
              self.handleInput()
        }))

olbrichj

let op1 = Operation()
op1.name = "Operation1"

OperationQueue.main.addOperations([op1], waitUntilFinished:false)
let operations = OperationQueue.main.operations

operations.map { op in
    if op.name == "Operation1" {
        op.cancel()
    }

olbrichj

URLSession.shared.dataTask(with: url!) { data, _, error in
    if error != nil {
        print(error)
        return
    }
    DispatchQueue.main.async {
        imageView.image = UIImage(data: data!)
    }
}.resume()

olbrichj

URLSession.shared.dataTask(with: backendurl!) { data, _, error in
    if error != nil {
        print(error)
        return
    }
    
    let imageurl = String(data: data!, encoding: String.Encoding.utf8) as String! // For simplicity response is only the URL
    URLSession.shared.dataTask(with: URL(string:imageurl!)!) { (data, response, error) in
        if error != nil {
            print(error)

olbrichj

public class ApiRequestDelegate:NSObject, URLSessionDelegate, URLSessionTaskDelegate,
URLSessionDataDelegate{
    
    // called once as soon as a response returns
    public func urlSession(session: URLSession, dataTask: URLSessionDataTask,
                           didReceiveResponse response: URLResponse,
                           completionHandler: (URLSession.ResponseDisposition) -> Void) {
        // store Response to further process it and call completion Handler to continue
    }
    

olbrichj

class NetworkOperation: Operation {
    var targetURL: String?
    var resultData: Data?
    var _finished = false
    override var isFinished: Bool {
        get {
            return _finished
        }
        set (newValue) {
            willChangeValue(for: \.isFinished)