The default value is {UIView.NoIntrinsicMetric, UIView.NoIntrinsicMetric}.
Some views, such as UIKit.UILabels, have a natural intrinsic size that is not related to the actual UIView.Frame that contains the entirety of the UIKit.UIView. This property allows the UIKit.UIView to tell the Auto Layout system what System.Drawing.SizeF it would prefer to be.
If a UIKit.UIView has no intrinsic size, it should return the default {UIView.NoIntrinsicMetric,UIView.NoIntrinsicMetric} value.