NSOperationQueue addOperations waitUntilFinished

Question

Hi, I am building an application using Swift. I need to process notifications in a specific order. So I'm trying to use addOperations waitUntilFinished.

Here is what I did:

let oldify = NSOperation()
    oldify.completionBlock = {
println("oldify")
}
let appendify = NSOperation()
    appendify.completionBlock = {
println("appendify")
}
let nettoyify = NSOperation()
    nettoyify.completionBlock = {
println("nettoyify")
}
NSOperationQueue.mainQueue().maxConcurrentOperationCount = 1
NSOperationQueue.mainQueue().addOperations([oldify, appendify, nettoyify], waitUntilFinished: true)

With this code, none of the operations are performed. When I try this:

NSOperationQueue.mainQueue().maxConcurrentOperationCount = 1
NSOperationQueue.mainQueue().addOperation(oldify)
NSOperationQueue.mainQueue().addOperation(appendify)
NSOperationQueue.mainQueue().addOperation(nettoyify)

Operations are performed, but not in the correct order.

Does anyone know what I'm doing wrong? I am sure of a fast but completely new to NSOperations.

Answer 1

A few problems:

• You study the behavior of completion block handlers. As stated in the documentation completionBlock:

  , . , .

  , ( completionBlock). , (), , () completionBlock completionBlock .., (c) .

• , . , , , , . .

• , :

  . , , isReady YES - , . , . . , , NSOperation.

  , - :

  let oldify = NSBlockOperation() {
      NSLog("oldify")
  }
  oldify.completionBlock = {
      NSLog("oldify completion")
  }
  
  let appendify = NSBlockOperation() {
      NSLog("appendify")
  }
  appendify.completionBlock = {
      NSLog("appendify completion")
  }
  
  appendify.addDependency(oldify)
  
  let nettoyify = NSBlockOperation() {
      NSLog("nettoyify")
  }
  nettoyify.completionBlock = {
      NSLog("nettoyify completion")
  }
  
  nettoyify.addDependency(appendify)
  
  let queue = NSOperationQueue()
  queue.addOperations([oldify, appendify, nettoyify], waitUntilFinished: false)
  

• , , waitUntilFinished. , , , waitUntilFinished.