Question

在发布iOS8之前，我下载了iOS8 SDK，观看我的应用程序是如何工作的。有时我的应用程序需要从服务器下载数据，我使用NSUrlSession。现在，当app准备下载会话时，会出现下一个警告：

+backgroundSessionConfiguration: is deprecated. Please use +backgroundSessionConfigurationWithIdentifier: instead。

之后我的应用程序因下一个异常而崩溃：

Unable to cast object of type 'MonoTouch.Foundation.NSUrlSessionTask' (Objective-C type: '__NSCFBackgroundDownloadTask') to type 'MonoTouch.Foundation.NSUrlSessionDownloadTask'.
Additional information:
    Selector: URLSession:downloadTask:didFinishDownloadingToURL:
    Method: Microsoft.Synchronization.ClientServices.NSUrlDownloadDelegate:DidFinishDownloading (MonoTouch.Foundation.NSUrlSession,MonoTouch.Foundation.NSUrlSessionDownloadTask,MonoTouch.Foundation.NSUrl)

创建NSUrlSession的代码：

NSUrlSessionConfiguration sessionConfiguration = NSUrlSessionConfiguration.BackgroundSessionConfiguration(urlSessioinId);
NSUrlDownloadDelegate downloadDelegate = new NSUrlDownloadDelegate();
NSUrlSession downloadSession = NSUrlSession.FromConfiguration(sessionConfiguration, downloadDelegate, new NSOperationQueue());

感谢您的帮助！

Answer 1

我在Objective-C中使用以下来解决这个错误：

NSURLSessionConfiguration *sessionConfig;

if ([[[UIDevice currentDevice] systemVersion] floatValue] >=8.0f)
{
    sessionConfig =[NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:@"downloads"];
}
else
{
    sessionConfig = [NSURLSessionConfiguration backgroundSessionConfiguration:@"downloads"];
}

Answer 2

这应该有用。

if(UIDevice.CurrentDevice.CheckSystemVersion(8, 0))
{
 configDownload = NSUrlSessionConfiguration.CreateBackgroundSessionConfiguration(sessionId);
}
else
{
configDownload = NSUrlSessionConfiguration.BackgroundSessionConfiguration(sessionId);
}

iOS8：不推荐使用backgroundSessionConfiguration

2 个答案: