title: iOS _OBJC_CLASS errors after adding a library to project
body: <p>I am trying to add PayU money sdk to my project. And after adding <code>libiOSCustomBrowser.a</code> file it gives errors:</p>
  
  <pre><code>    ld: warning: directory not found for option '-L/Users/Jenaveve/myApp/Utilities/PayUSdk'
  Undefined symbols for architecture x86_64:
    "_OBJC_CLASS_$_WKUserContentController", referenced from:
        objc-class-ref in libiOSCustomBrowser.a(PUCBWebVC.o)
    "_OBJC_CLASS_$_WKWebView", referenced from:
        objc-class-ref in libiOSCustomBrowser.a(PUCBMagicRetry.o)
        objc-class-ref in libiOSCustomBrowser.a(PUCBBaseConnection.o)
        objc-class-ref in libiOSCustomBrowser.a(PUCBWebVC.o)
        objc-class-ref in libiOSCustomBrowser.a(CBWKConnection.o)
    "_OBJC_CLASS_$_WKWebViewConfiguration", referenced from:
        objc-class-ref in libiOSCustomBrowser.a(PUCBWebVC.o)
  ld: symbol(s) not found for architecture x86_64
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  </code></pre>
  
  <p>In build phases, in Link Binary with Libraries, this reference exists. What is wrong?</p>