Instance Method

frame(forAlignmentRect:)

Returns the view’s frame for a given alignment rectangle.

Declaration

func frame(forAlignmentRect alignmentRect: CGRect) -> CGRect

Parameters

alignmentRect

The alignment rectangle whose corresponding frame is desired.

Return Value

The frame for the specified alignment rectangle

Discussion

The constraint-based layout system uses alignment rectangles to align views, rather than their frame. This allows custom views to be aligned based on the location of their content while still having a frame that encompasses any ornamentation they need to draw around their content, such as shadows or reflections.

The default implementation returns alignmentRect modified by the view’s alignmentRectInsets. Most custom views can override alignmentRectInsets to specify the location of their content within their frame. Custom views that require arbitrary transformations can override alignmentRect(forFrame:) and frame(forAlignmentRect:) to describe the location of their content. These two methods must always be inverses of each other.