在Swift中，如何在GCD主线程上调用带有参数的方法? [英] In Swift how to call method with parameters on GCD main thread?

问题描述

在我的应用中，我有一个函数，该函数可以创建NSRURLSession并使用发送一个NSURLRequest

In my app I have a function that makes an NSRURLSession and sends out an NSURLRequest using

sesh.dataTaskWithRequest(req, completionHandler: {(data, response, error)

在此任务的完成块中，我需要进行一些计算，以将UIImage添加到调用的viewcontroller中.我有一个叫做

In the completion block for this task, I need to do some computation that adds a UIImage to the calling viewcontroller. I have a func called

func displayQRCode(receiveAddr, withAmountInBTC:amountBTC)

执行添加UIImage的计算.如果我尝试在完成块内运行添加视图的代码，则Xcode会引发错误，提示我在后台进程中无法使用布局引擎.因此，我在SO上找到了一些代码，试图在主线程上将方法排队:

that does the UIImage-adding computation. If I try to run the view-adding code inside of the completion block, Xcode throws an error saying that I can't use the layout engine while in a background process. So I found some code on SO that tries to queue a method on the main thread:

let time = dispatch_time(DISPATCH_TIME_NOW, Int64(0.0 * Double(NSEC_PER_MSEC)))
                    dispatch_after(time, dispatch_get_main_queue(), {
                        let returned = UIApplication.sharedApplication().sendAction("displayQRCode:", to: self.delegate, from: self, forEvent: nil)
                        })

但是，我不知道如何在此函数调用中添加参数"receiveAddr"和"amountBTC".我该怎么做，或者有人可以建议将方法调用添加到应用程序主队列的最佳方法?

However, I don't know how to add the parameters "receiveAddr" and "amountBTC" to this function call. How would I do this, or can someone suggest an optimal way for adding a method call to the application's main queue?

推荐答案

只需将其写在completion handler中.无需使用dispatch_after

Just write this in completion handler.No need to use dispatch_after

dispatch_async(dispatch_get_main_queue(), {
  let delegateObj = UIApplication.sharedApplication().delegate as YourAppDelegateClass
  delegateObj.addUIImage("yourstring")
})

快速3/4:

DispatchQueue.main.async { 
  let delegateObj = UIApplication.sharedApplication().delegate as YourAppDelegateClass
  delegateObj.addUIImage("yourstring")
}

还用于在主队列上发送后

DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
  // your code here
}

用您的委托类替换YourAppDelegateClass

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