在swift3和xcode 8.1中引入了一个新的DispatchQueue，我可以使用它备份到ios 9.0吗？

Question

在Xcode 8.1

//Move to a background thread to do some long running work 
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) { 
    let image = self.loadOrGenerateAnImage() 
    // Bounce back to the main thread to update the UI 
    dispatch_async(dispatch_get_main_queue()) { 
     self.imageView.image = image 
    } 
} 

我得到一些错误，与上面的代码，它表明我使用DispatchQueue这是iOS的10.0，可如何清除这个错误，并与ios9.0兼容。我将使用@available和#available以确定本运行 平台

Answer 1

的SWIFT 3，你可以做这样的

DispatchQueue.global(qos: .background).async { 
    let image = self.loadOrGenerateAnImage() 
    DispatchQueue.main.async { 
     self.imageView.image = image 
    } 
} 

Answer 2

Yes you can use that in iOS 8 or 9. In iOS that it will be different. 
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) { 
      let image = self.loadOrGenerateAnImage() 
      // Bounce back to the main thread to update the UI 
      dispatch_async(dispatch_get_main_queue()) { 
       self.imageView.image = image 
      } 
     }