As your know , when you useASIHttpRequestin Project. We should modify the Header Search Path.
It’s very easy to modify it in XCode 3, but when upgrade to xcode 4, we hardly to find the text input to modify.
The steps is below:
Fist, select your project in the Project Navigator.
Second, select the Building Settings.
Third, change the “Basic” to “All” in the Tab Navigator.
FROM:http://www.ioslib.com/tutorial/xcode/how-to-modify-the-header-search-paths-in-xcode-4/