title: Xcode gives Apple Mach-O linker error
body: <p>I just compiled a project and Xcode returns these two errors which don't seem to be my code's fault. How do I fix them?</p>
  
  <pre><code>Undefined symbols for architecture i386:
    "_vImageBoxConvolve_ARGB8888", referenced from:
        -[UIImage(Blur) boxblurImageWithBlur:] in UIImage+Blur.o
  ld: symbol(s) not found for architecture i386
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  </code></pre>