title: "unrecognized selector sent to instance" to a static library despite ObjC flag
body: <p>I'm getting a runtime error in my application:</p>
  
  <blockquote>
    <p><code>2011-05-17 09:42:31.124 rxsync[67464:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSMutableURLRequest setHTTPBodyWithFormMultipartValues:fileNames:contentTypes:usingBoundary:]: unrecognized selector sent to instance 0x4e3cd90'</code></p>
  </blockquote>
  
  <p>This method, <code>NSMutableURLRequest setHTTPBodyWithFormMultipartValues: fileNames: contentTypes: usingBoundary:]</code>, is defined by a static library that's part of my .xcworkspace.</p>
  
  <p>Here's what I've checked so far:</p>
  
  <ol>
  <li>The static library is included in my <strong>Link Binary With Libraries</strong> phase.</li>
  <li>I have ObjC in the Other Linker Flags (<code>OTHER_LDFLAGS = -ObjC</code>) in my application. (In fact, I have it in my static library, too, since it's based on the same xcconfig file.)</li>
  <li>The signature is the same in my .h and .m file.</li>
  <li>The static library has <strong>definitely</strong> been rebuilt.</li>
  <li>I have verified that the object I'm sending the message to is valid.</li>
  </ol>
  
  <p>What possibilities am I missing?</p>
  
  <p>I'm using Xcode 4.0.2. This is an iPhone target.</p>