Build Error - missing required architecture i386 in file

This happens when you add a framework to your project and unintentionally copy the framework into your project directory.

The fix is to check your project directory (where you store your project on disk) for any iphone SDK *.Framework files and delete them.

Project will build fine afterwards.

I had this same problem, and the solution turned out to be an easy fix. Backup then open project.pbxproj (located inside your project file bundle) in TextMate or TextEdit and search for the section titled "/* Begin XCBuildConfiguration section */". Look for a key named FRAMEWORK_SEARCH_PATHS and delete it and it's contents (once per build configuration, so I removed it in two places). Here is an example of what I deleted:

FRAMEWORK_SEARCH_PATHS = (
"$(inherited)",
"\"$(DEVELOPER_DIR)/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS3.1.sdk/System/Library/Frameworks\"",);

My project now build for both the iPhone device and the iPhoneSimulator.

What has happened here is that Xcode has mysteriously added a "Framework Search Paths" entry that points to a particular iPhone device SDK. For example, mine was recently set to:

$(DEVELOPER_DIR)/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS2.2.1.sdk/System/Library/Frameworks

This leads the compiler to find frameworks of the incorrect architecture. Removing any values under the "Framework Search Paths" key in your target's build settings will resolve the issue.

I just wanted to mention that in XCode if you go to "Edit Project Settings" and find "Search Paths" There is a field for "Framework Search Paths". Updating this should fix the problem, without having to hack the project file!

Cheers!

Jesse