iOS foreground and background interaction problems

do a login screen on iOS. . I do not know how to describe their problems Eph. . Similar qq login screen that I put the user to enter a user name and password, pass the background, so that the background to judge a user name and password are correct or not, and then returns a value to me and tell me the username and password are correct, the user name and password are correct successful landing, otherwise login failed. . . . The problem now is that I do not know how to pass the username and password back? ? Do not know how to pass something back to me? ? Can you give me on this aspect Detailed look? Or give me some keywords? Or connect? Thank you pull. . What is the reception? What is the background? My understanding is that the reception is the iphone interface, users see. . The background is some technical support, data support. . .
Reply:
1.HTTP communication, you can refer to: ASIHTTPRequest
2.Socket communication, you can refer to: AsyncSocket
Under the proposed landlord Baidu knowledge, a lot of
Reply:

cited a floor h98458 reply:

1.HTTP communication, you can refer to: ASIHTTPRequest
2.Socket communication, you can refer to: AsyncSocket
Under the proposed landlord Baidu knowledge, a lot

solution to this problem http://blog.csdn.net/willingyatou/article/details/12617073