Autolayout - UILabel shrinks in width after orientation change, cause by another UILabel which is supposed to auto-adjust font size

Question

I have 2 UILabel side-by-side horizontally using auto-layout as following:

1. 1st-Label is full-width (like sizeToFit)
2. 2nd-Label has adjustsFontSizeToFitWidth = true

On launch everything is fine, when returning from landscape to portrait 1st-Label shrinks to zero width.

Constraints are following:

• 1st Label: H:|-0-[1stLabel] , V:[1stLabel]-0-|
• 2nd Label: H:[2ndLabel]-0-| , V:[2ndLabel]-0-|
• Leading/Trailing Relation Constraint: H:[1stLabel]-(>=1)-[2ndLabel]

Answer 1

将标签1的抗压性优先级设置为1000

Answer 2

我错过了在2nd-Label上设置ContentCompressionResistancePriority的方法：

secondLabel.setContentCompressionResistancePriority(.defaultLow, for:.horizontal)