我有这个:
<RelativeLayout HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand" BackgroundColor="Red">
<StackLayout Orientation="Vertical" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand" Padding="0,15" Spacing="10"></StackLayout>
</RelativeLayout>
但是由于某种原因，即使是强硬的RelativeLayout也会明显扩展，而StackLayout却没有。如何让StackLayout水平拉伸并填充屏幕的整个宽度/高度？
对于RelativeLayout，您需要使用约束，而不是垂直/水平选项。应该是这样的
<StackLayout Orientation="Vertical" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand" Padding="0,15" Spacing="10"
RelativeLayout.WidthConstraint=
"{ConstraintExpression Type=RelativeToParent,
Property=Width,
Factor=1}"
RelativeLayout.HeightConstraint=
"{ConstraintExpression Type=RelativeToParent,
Property=Height,
Factor=1}">
</StackLayout>
