One of the first two days of a pit about AutoLayout.

For a view, add it to a superview and set the constraint, for example, to set the height constraint to 100

If you manipulate the view again, add it to another superview, and then set the constraint again, the constraint that was previously attached to the view will not be emptied because of its superview change, and there is a constraint violation.

How to resolve:

When you add a constraint again, you should first empty the previous constraint, and for masonry, use Remakeconstraint instead of makeconstraints.

One of the first two days of a pit about AutoLayout.