在委托方法中添加完成处理程序

我很难理解完成处理程序。我试图让一个函数（purchaseRequest）等待，直到另一个函数（didReceiveResponse）不被我调用，而是作为委托完成。有人能给我一个关于如何实现这一目标的指针吗？在委托方法中添加完成处理程序

func productsRequest(request: SKProductsRequest, didReceiveResponse response: SKProductsResponse) { 
    print("response received") 
    if response.products.count != 0 { 
     productsArray = response.products[0] 
     print(productsArray) 
    } else { print("No Products Found") } 
} 

func purchaseRequest() { 
    requestProductInfo() 

    //NEED TO HOLD UNTIL didReceiveResponse (which, as a delegate method, is not called by me) IS DONE. 
     print("Product1: \(self.productsArray)") 
    let aSC = UIAlertController(title: "Premium App Required", message: "Premium App is Required for this feature. Would you like to purchase it for $0.99?", preferredStyle: UIAlertControllerStyle.ActionSheet) 
    let buyAction = UIAlertAction(title: "Purchase", style: UIAlertActionStyle.Default) { (action) -> Void in 
     let payment = SKPayment(product: self.productsArray) 
     SKPaymentQueue.defaultQueue().addPayment(payment) 

    } 
    let cancelAction = UIAlertAction(title: "Cancel", style: UIAlertActionStyle.Cancel) { (action) -> Void in 
    } 
    aSC.addAction(buyAction) 
    aSC.addAction(cancelAction) 
    self.presentViewController(aSC, animated: true, completion: nil) 
}

来源

2016-01-18 Jacobo Koenig

•推进度微调视图控制器

•使purchaseRequest后立即返回requestProductInfo()

•requestProductInfo()后的委托方法捕获代码的新方法

•，dispatch_async()到主队列并调用新方法

•在新方法中，弹出微调视图控制器，然后进行高级购买舞蹈

来源

2016-01-18 19:24:49 bbum

谢谢！我所做的是调用requestProductInfo（），然后使用dispatch_async（）在didReceiveResponse委托内部进行purchaseRequest！ –

@JacoboKoenig太棒了！小心“一路阻挡”陷阱;回调处理程序调用异步方法传递回调处理程序，该回调处理程序使用回调处理程序调用另一个方法。（我充满罪责）。在某个时候，您想要将回调处理程序重构为自己的方法，然后调用它。 – bbum

在委托方法中添加完成处理程序

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