我的代码中有以下警告(XCode4.3/iOS4/5)-从不兼容类型“MainViewController*”分配给“id”本节提出警告--(IBAction)sendInAppSMS:(id)sender{MFMessageComposeViewController*controller=[[[MFMessageComposeViewControlleralloc]init]autorelease];if([MFMessageComposeViewControllercanSendText]){controller.body=@"Atestmessagefromhttp://www.