When putting multiline label (with linebreak set to Word Wrap) into a stack view, the label immediately loses the linebreak and displays the label text in one line instead.<
For those working with a storyboard or XIB file trying to embed a UILabel in a horizontal stack view, do NOT add constraints to anything that will you plan on putting in a stack view before the stack view is created. This will cause errors and/or an inability to wrap text.
Instead, do this in addition to the suggestions made by Andy and pmb.
UILabel in UIView.UILabel lines = 0.Not sure why this order of operations makes a difference, but it does.