Add Layout Issues example

[vlas-voloshin]

Reveal 6 has introduced detection of layout ambiguity and broken constraints. Revert needs a corresponding example to help with regression testing of this functionality. The example should contain:

• A constraint that gets broken by Auto Layout.
  • Making this constraint break automatically will trip UIViewAlertForUnsatisfiableConstraints breakpoints unexpectedly, so maybe it's better to "break" them by a tap of a button or something like that.
• Views with missing constraints for width, height, horizontal position, vertical position, scrollable content width, scrollable content height. Several views with a combination a few of these dimensions would be nice.
• Views with ambiguous dimensions (same as above). The easiest way to create an ambiguity is to use inequality constraints not paired with an equality constraint on the same dimension.
• Including a layout guide with missing constraints or ambiguous dimensions would be a plus.

[orj]

@yimingc2 Does your #38 PR cover all the cases Vlas has mentioned here?

[yimingc2]

@orj Do you know what does the first bullet mean? As far as I know, only when make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints explicitly will trigger this breakpoint. What does it mean by making a constraint break automatically?

[orj]

@yimingc2 I think perhaps Vlas was concerned about people with an Xcode User breakpoint configured on the symbol UIViewAlertForUnsatisfiableConstraints having it trigger automatically when they are debugging Revert.

I imagine he had a breakpoint configured this way. It is a good tool for noticing when you're layout code is getting broken when you don't expect it to.

The "user experience" of having Revert break a constraint as soon as the example is pushed onto the UINavigationController would be less than ideal in this case. So having the example break the constraint on request (via a button) would be a nicer developer user experience.

Configure a Symbolic breakpoint on UIViewAlertForUnsatisfiableConstraints and visit your example to see what I mean.