New MaskedCorners Property In CALayer

Looks like there’s a new property of CALayer that, according to documentation, allows you to specify which corners of a CALayer receive the masking treatment when setting the cornerRadius property. New value is called maskedCorners and it takes a new CACornerMask struct instance.

This should be really useful. Came upon it because I’m adding a padding view to the bottom of the DrinkSelector (The bottom bar of the main screen with the 5 drink type icons) to Drink Keeper for iPhone X support, and only wanted the rounded corners on the bottom to follow the screen. Looks like Apple knew exactly what I needed!

Apple’s online docs don’t have any information, but here is the doc block from Xcode.

/* Defines which of the four corners receives the masking when using
 * cornerRadius property. Defaults to all four corners. */

@property CACornerMask maskedCorners
CA_AVAILABLE_STARTING (10.13, 11.0, 11.0, 4.0);
/* Bit definitions for `maskedCorners' property. */

typedef NS_OPTIONS (NSUInteger, CACornerMask)
  kCALayerMinXMinYCorner = 1U << 0,
  kCALayerMaxXMinYCorner = 1U << 1,
  kCALayerMinXMaxYCorner = 1U << 2,
  kCALayerMaxXMaxYCorner = 1U << 3,