It happens to the best of us. We're going along, composing some UIViews in our app. We're styling them, configuring them, we can't wait to try them out. That's when we see it. A big, empty, unescapable void of nothingness right where our views should be! 😱

Today we'll look at some tips to solve a case of missing UIViews.

First, we should arm ourselves with tools to help inspect what's going on. Xcode's own View Debugger is a great place to start, and Reveal.app is a fantastic third-party solution.

Whether it's one of these tools, or simply writing some in-depth logging functions, our first step should be to look at both our view hierarchy and its layout for anything funky.

print(UIApplication.sharedApplication().keyWindow?
  .performSelector("recursiveDescription"))

We can use private functions like recursiveDescription to print out a handy tree-view of our views to Xcode's Console.

Most of these debugging sessions stop here, as the problem often involves a view not being in the correct place in the hierarchy, or Auto Layout has gone and done something wacky with our views' locations.

If we're still stuck though, here are some sanity checks we can perform:

• Are any views hidden?
• How about transparent? (0 alpha)
• Is it masked via a maskLayer?
• Does it have a CGRectZero frame?
• Is the key UIWindow a weird size or in a weird place?

Try making each view a specific ugly color (the static .XColor() functions on UIColor work wonders here).

• Is another view covering it up?
• Is .clipsToBounds enabled and a strange frame/bounds is causing the view to be clipped?

If all else fails, comment out everything, and add it back one bit at a time until something fails.

Happy 🐞 hunting!