I get the following error when trying to run my application. There are no errors in the source code
<p>I get the following error when trying to run my application. There are no errors in the source code.</p>

<pre><code>                      Undefined symbols:
  "__Block_object_dispose", referenced from:
      ___destroy_helper_block_2 in myprojectAppDelegate.o
      ___destroy_helper_block_1 in myprojectAppDelegate.o

  "__NSConcreteStackBlock", referenced from:
      __NSConcreteStackBlock$non_lazy_ptr in myprojectAppDelegate.o
     (maybe you meant: __NSConcreteStackBlock$non_lazy_ptr)

  "__Block_object_assign", referenced from:
      ___copy_helper_block_2 in myprojectAppDelegate.o
      ___copy_helper_block_1 in myprojectAppDelegate.o

ld: symbol(s) not found
collect2: ld returned 1 exit status
</code></pre>
