public struct UIRectCorner : OptionSet {
public init(rawValue: UInt)
public static var topLeft: UIRectCorner { get }
public static var topRight: UIRectCorner { get }
public static var bottomLeft: UIRectCorner { get }
public static var bottomRight: UIRectCorner { get }
public static var allCorners: UIRectCorner { get }
}