我們可以繼承NSOperationQueue嗎？

Question

我想子類NSOperationQueue跟蹤互聯網依賴的操作是否成功完成或沒有。是否可以繼承NSOperationQueue？

Answer 1

你可以很好的子類NSOperationQueue。

下面子的分級OperationQueue

import Foundation 
    class AsynchronousOperation: Operation { 
     override var isAsynchronous: Bool { return true } 
     override var isExecuting: Bool { return state == .executing } 
     override var isFinished: Bool { return state == .finished } 

     var state = State.ready { 
      willSet { 
       willChangeValue(forKey: state.keyPath) 
       willChangeValue(forKey: newValue.keyPath) 
      } 
      didSet { 
       didChangeValue(forKey: state.keyPath) 
       didChangeValue(forKey: oldValue.keyPath) 
      } 
     } 

     enum State: String { 
      case ready = "Ready" 
      case executing = "Executing" 
      case finished = "Finished" 
      fileprivate var keyPath: String { return "is" + self.rawValue } 
     } 

     override func start() { 
      if self.isCancelled { 
       state = .finished 
      } else { 
       state = .ready 
       main() 
      } 
     } 

     override func main() { 
      if self.isCancelled { 
       state = .finished 
      } else { 
       state = .executing 
      } 
     } 
    } 

如何用一個例子： 1.呼叫super.main()當覆蓋main方法，調用super.start()當覆蓋start方法。 2.當操作完成或取消設置self.state = .finished'

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