UIPopoverBackgroundView contentViewInsets must be implemented by subclassers
问题 I'm implementing a custom PopoverBackgroundView, and as specified at Swift documentation I gotta implement the methods as follow: class SettingsPopoverBackgroundView: UIPopoverBackgroundView { override var arrowOffset: CGFloat { get { return 0.0 } set { super.arrowOffset = newValue } } override var arrowDirection: UIPopoverArrowDirection { get { return UIPopoverArrowDirection.Up } set { super.arrowDirection = newValue } } func contentViewInsets() -> UIEdgeInsets { return UIEdgeInsetsMake(10,