线程+多个窗口导致奇怪的错误

Question

我在swift中有两个窗口，其中一个就像登录对话框，它将NSURLConnection.sendAsynchronousRequest发送到服务器以进行身份验证。一旦它得到响应，窗口就应该关闭。

当我关闭窗口（从登录窗口类或主窗口类）时，我会收到以下错误：

This application is modifying the autolayout engine from a background thread, which can lead to engine corruption and weird crashes. This will cause an exception in a future release.

我已经尝试了各种后台线程等。但我认为问题是我正在关闭异步NSURLConnection请求仍然挂起的窗口。

我从登录窗口发送异步请求的代码：

dispatch_async(dispatch_get_main_queue(), {
            let queue:NSOperationQueue = NSOperationQueue()
            NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) -> Void in
                var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil
                let jsonResult: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options:NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary
                let result: NSString = NSString(data: data, encoding: NSUTF8StringEncoding)!
                let expectedString = "special auth string"!
                if(result == expectedString) {
                    self.callback.loginOK()
                } else {
                    self.output.stringValue = result
                }
                return
            })
        })

类的回调成员是派生它的父视图控制器，然后我从主应用程序窗口使用loginVC.view.window?.close()关闭登录窗口。这导致了错误。

Answer 1

问题是NSURLConnection.sendAsynchronousRequest将始终在辅助线程中运行，因此，尽管您从主线程显式调用它，但它的回调仍将从该辅助线程调用。您不需要在主线程中包装NSURLConnectionsendAsynchronousRequest，而是使用dispatch_async包装您的"self.callback.loginOK（）"以在主线程运行，以确保在辅助线程中不会发生与UI相关的操作。类似这样的东西-

let queue:NSOperationQueue = NSOperationQueue()
            NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) -> Void in
                var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil
                let jsonResult: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options:NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary
                let result: NSString = NSString(data: data, encoding: NSUTF8StringEncoding)!
               dispatch_async(dispatch_get_main_queue() {
                let expectedString = "special auth string"!
                if(result == expectedString) {
                    self.callback.loginOK()
                } else {
                    self.output.stringValue = result
                }
              })
                return
            })