rollAngle
The roll angle of the face specified in degrees.
Declaration
var rollAngle: CGFloat { get }Discussion
The roll angle represents the side-to-side tilt of the face relative to the metadata’s bounding rectangle. A value of 0.0 yields a face that is level relative to the picture, whereas a value of 90 yields a face that is perpendicular relative to the picture.
You must check the value of the hasRollAngle property before accessing this property. If the value in the hasRollAngle property is false, reading the value in this property raises an exception.