IOS参考官方文档:
https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/URLLoadingSystem/Tasks/UsingNSURLConnection.html
如果你想下载URL所制定的内容,必须要要实现这个协议:NSURLConnectionDelegate 其中的几个方法:
In order to download the contents of a URL, an application needs to provide a delegate object that, at a minimum, implements the following delegate methods:
connection:didReceiveResponse:
connection:didReceiveData:
connection:didFailWithError:
connectionDidFinishLoading:
1:如果执行了:connection:didFailWithError: 消息,那么从NSError可以提取: [error code] 和 [error userInfo](返回一个字典)
我们可以从字典中抽取出:NSURLErrorFailingURLStringErrorKey 所对应的消息:
NSString object for the URL which caused a load to fail
如果执行这个消息的话,其他的代理方法将不会再执行!
it receives no further delegate messages for the specified connection.
相关概念:
服务器端验证:
continueWithoutCredentialForAuthenticationChallenge(消息)
sendSynchronousRequest:returningResponse:error:(发送同步请求)
疑问:
1:同步发送请求和异步发送请求在IOS中有什么差别呢?
2:如何创建认证证书或者认证凭证呢?