Error in Build - Missing SDK

I downloaded some Application samples from a website. It used to work but when I went back to Xcode (After a couple of months) I tried them and it gives me this error.

error: There is no SDK with the name 开发者_Python百科 or path 'iphoneos2.0'

I tried looking for a file called "iphoneos2.0" and tried looking for a highlighted code but nothing.

Could anyone help me please?

The Base SDK of your downloaded app's Target has set to iphoneos2.0. Change the Base SDK of the Target from iphoneos2.0 to a iOS version which is available.

To change the Build Settings in (Xcode 3.2) - Goto Project -> Edit Project Settings menu. Or, Double-click the project name in the project tree in Xcode.

To change the Build Settings in (Xcode 4) - Select the project name in the project tree. It will open the Project Settings in the document area of Xcode.

In the project settings, search for Base SDK.