title: Xcode playground gets stuck on 'Running playground' or 'Launching simulator' and won't run the code, what to do?
body: <p>Every time I create a new playground in order to test some code, Xcode gets stuck and won't run the code. It simply presents 'Running playground' or 'Launching simulator' statement at the top of the screen with the loading icon promisingly spinning next to it but nothing happens. Sometimes this continues indefinitely and sometimes Xcode halts and prints this to console :</p>
  
  <pre><code>Playground execution failed: error: Couldn't lookup symbols:
  __swift_FORCE_LOAD_$_swiftCoreImage 
  __swift_FORCE_LOAD_$_swiftFoundation 
  _playground_log_hidden 
  _playground_logger_initialize 
  _playground_log_postprint 
  
  thread #1: tid = 0xc0cd0, 0x000000010ea7c3c0 MyPlayground`executePlayground, queue = 'com.apple.main-thread', stop reason = breakpoint 1.2
  
  frame #0: 0x000000010ea7c3c0 MyPlayground`executePlayground
  frame #1: 0x000000010ea7b9c0 MyPlayground`__37-[XCPAppDelegate enqueueRunLoopBlock]_block_invoke + 32 
  frame #2: 0x000000010f59625c CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12
  frame #3: 0x000000010f57b304 CoreFoundation`__CFRunLoopDoBlocks + 356
  frame #4: 0x000000010f57aa75 CoreFoundation`__CFRunLoopRun + 901
  frame #5: 0x000000010f57a494 CoreFoundation`CFRunLoopRunSpecific + 420
  frame #6: 0x0000000114985a6f GraphicsServices`GSEventRunModal + 161
  frame #7: 0x0000000110124f34 UIKit`UIApplicationMain + 159
  frame #8: 0x000000010ea7b6e9 MyPlayground`main + 201
  frame #9: 0x0000000112ad268d libdyld.dylib`start + 1
  frame #10: 0x0000000112ad268d libdyld.dylib`start + 1
  </code></pre>
  
  <p>I am running Xcode 8.0 (8A218a) on macOS Sierra 10.12. <br></p>
  
  <p><strong>Hardware</strong>: <br>
  MacBook Pro (13" Mid-2012) <br>
  2,5 GHz Intel Core i5 <br>
  4 GB 1600 MHz Ram DDR3</p>
  
  <p>I have looked around but at least neither of these threads have provided an answer: <br>
  <a href="https://forums.developer.apple.com/thread/5902" rel="noreferrer">https://forums.developer.apple.com/thread/5902</a> <br>
  <a href="https://github.com/jas/playground/issues/9" rel="noreferrer">https://github.com/jas/playground/issues/9</a></p>
  
  <p>Things I have already tried with zero success:</p>
  
  <ul>
  <li>Restarting Xcode</li>
  <li>Reinstalling Xcode (downgraded to 7.3 but since that didn't help I
  upgraded back to 8.0)</li>
  <li>Restarting the machine</li>
  <li>Creating a new playground</li>
  </ul>
  
  <p>Do you have any ideas on how to solve this problem? I am new to programming and eagerly trying to learn Swift but Xcode is making it practically impossible...</p>
  
  <p>Thank you in advance, cheers.</p>