title: Why do crashes in iOS relating to dyld_stub_binder occur?
body: <p>It's widely known that dynamic link libraries aren't allowed in iOS apps, they may only link to dynamic system libraries.  But I do run into some pretty confusing crashes with the 3rd frame from the top of the stack being dyld_stub_binder.  </p>
  
  <p>It's tough to find some solid information, but I'm guessing that dyld_stub_binder actually performs late linking of a dynamic system library.</p>
  
  <p>I tend to run into crashes where the exception is EXC_BREAKPOINT UNKNOWN and the crash always seems to occur in the context of dyld_stub_binder.</p>
  
  <p>The implementation of <a href="http://www.opensource.apple.com/source/dyld/dyld-132.13/src/dyld_stub_binder.s" rel="noreferrer">dyld_stub_binder</a> is on the apple open source website.  I don't quite understand the assembly, but perhaps someone who does could interpret why this error happens or whether or not it's something that is out of the application's direct control.  The assembly code may not be useful though, as I'm talking about the iOS (arm) implementation and this code is i386 and x86_64.</p>
  
  <p>EDIT: An interesting piece of information is that I think I started seeing this crash during efforts for porting to arm64.  Is it possible that a runtime exception like this is due to some kind of misalignment?</p>