olbrichj

func executeOnMain() {
  if !Thread.isMainThread {
    DispatchQueue.main.async(execute: {() -> Void in
      executeOnMain()
    })
    return
  }
  
  // do something
}

olbrichj

OperationQueue.main

olbrichj

let operationQueue: OperationQueue = OperationQueue()

olbrichj

let operationQueue: OperationQueue = OperationQueue()
operationQueue.maxConcurrentOperationCount = 1

olbrichj

let op = DemoOperation()
OperationQueue.addOperations([op], waitUntilFinished: false)

op.cancel()

olbrichj

precedencegroup OperationChaining {
    associativity: left
}
infix operator ==> : OperationChaining

@discardableResult
func ==><T: Operation>(lhs: T, rhs: T) -> T {
    rhs.addDependency(lhs)
    return rhs
}

olbrichj

let op1 = Operation()

op.completionBlock = {
    print("done")
}

olbrichj

import Foundation

class AsyncOperation: Operation {
    override var isAsynchronous: Bool {
        return true
    }
    
    var _isFinished: Bool = false
    
    override var isFinished: Bool {

olbrichj

import Foundation

class TextOperation: AsyncOperation {
    let text: String
    
    init(text: String) {
        self.text = text
    }
    
    override func execute() {

olbrichj

import Foundation

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