How to set cornerRadius for only top-left and top-

Question

Is there a way to set cornerRadius for only top-left and top-right corner of a UIView?

I tried the following, but it end up not seeing the view anymore.

UIView *view = [[UIView alloc] initWithFrame:frame];

CALayer *layer = [CALayer layer];
UIBezierPath *shadowPath = [UIBezierPath bezierPathWithRoundedRect:frame byRoundingCorners:(UIRectCornerTopLeft|UIRectCornerTopRight) cornerRadii:CGSizeMake(3.0, 3.0)];
layer.shadowPath = shadowPath.CGPath;
view.layer.mask = layer;

Answer 1

This is how you can set a corner radius for each corner of a button with Xamarin in C#:

var maskPath = UIBezierPath.FromRoundedRect(MyButton.Bounds, UIRectCorner.BottomLeft | UIRectCorner.BottomRight,
    new CGSize(10.0, 10.0));
var maskLayer = new CAShapeLayer
{
    Frame = MyButton.Bounds,
    Path = maskPath.CGPath
};
MyButton.Layer.Mask = maskLayer;

Answer 2

I am not sure why your solution did not work but the following code is working for me. Create a bezier mask and apply it to your view. In my code below I was rounding the bottom corners of the _backgroundView with a radius of 3 pixels. self is a custom UITableViewCell:

UIBezierPath *maskPath = [UIBezierPath
    bezierPathWithRoundedRect:self.backgroundImageView.bounds
    byRoundingCorners:(UIRectCornerBottomLeft | UIRectCornerBottomRight)
    cornerRadii:CGSizeMake(20, 20)
];

CAShapeLayer *maskLayer = [CAShapeLayer layer];

maskLayer.frame = self.bounds;
maskLayer.path = maskPath.CGPath;

self.backgroundImageView.layer.mask = maskLayer;

Swift version with some improvements:

let path = UIBezierPath(roundedRect:viewToRound.bounds, byRoundingCorners:[.TopRight, .BottomLeft], cornerRadii: CGSizeMake(20, 20))
let maskLayer = CAShapeLayer()

maskLayer.path = path.CGPath
viewToRound.layer.mask = maskLayer

Swift 3.0 version:

let path = UIBezierPath(roundedRect:viewToRound.bounds,
                        byRoundingCorners:[.topRight, .bottomLeft],
                        cornerRadii: CGSize(width: 20, height:  20))

let maskLayer = CAShapeLayer()

maskLayer.path = path.cgPath
viewToRound.layer.mask = maskLayer

Swift extension here

Answer 3

In swift 4.1 and Xcode 9.4.1 onwards this code is enough

//In viewDidLoad
if #available(iOS 11.0, *){
        detailsSubView.clipsToBounds = false
        detailsSubView.layer.cornerRadius = 10
        detailsSubView.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaXMinYCorner]
} else {
      //For lower versions
}

But for lower versions

let rectShape = CAShapeLayer()
    rectShape.bounds = detailsSubView.frame
    rectShape.position = detailsSubView.center
    rectShape.path = UIBezierPath(roundedRect: detailsSubView.bounds,    byRoundingCorners: [.topLeft , .topRight], cornerRadii: CGSize(width: 20, height: 20)).cgPath
    detailsSubView.layer.mask = rectShape

If you are using AutoResizing in storyboard write this in viewDidLayoutSubviews

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()

if #available(iOS 11.0, *){
        detailsSubView.clipsToBounds = false
        detailsSubView.layer.cornerRadius = 10
        detailsSubView.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner]
    }else{
        let rectShape = CAShapeLayer()
        rectShape.bounds = detailsSubView.frame
        rectShape.position = detailsSubView.center
        rectShape.path = UIBezierPath(roundedRect: detailsSubView.bounds,    byRoundingCorners: [.topLeft , .topRight], cornerRadii: CGSize(width: 20, height: 20)).cgPath
        detailsSubView.layer.mask = rectShape
    }
}

Answer 4

Emma: .TopRight and .BottomRight are not working for you perhaps because the call to view.roundCorners is done BEFORE final view bounds are calculated. Note that the Bezier Path derives from the view bounds at the time it is called. For example, if auto layout will narrow the view, the round corners on the right side might be outside the view. Try to call it in viewDidLayoutSubviews, where the view's bound is final.

Answer 5

All of the answers already given are really good and valid (especially Yunus idea of using the mask property).

However I needed something a little more complex because my layer could often change sizes which mean I needed to call that masking logic every time and this was a little bit annoying.

I used swift extensions and computed properties to build a real cornerRadii property which takes care of auto updating the mask when layer is layed out.

This was achieved using Peter Steinberg great Aspects library for swizzling.

Full code is here:

extension CALayer {
  // This will hold the keys for the runtime property associations
  private struct AssociationKey {
    static var CornerRect:Int8 = 1    // for the UIRectCorner argument
    static var CornerRadius:Int8 = 2  // for the radius argument
  }

  // new computed property on CALayer
  // You send the corners you want to round (ex. [.TopLeft, .BottomLeft])
  // and the radius at which you want the corners to be round
  var cornerRadii:(corners: UIRectCorner, radius:CGFloat) {
    get {
      let number = objc_getAssociatedObject(self, &AssociationKey.CornerRect)  as? NSNumber ?? 0
      let radius = objc_getAssociatedObject(self, &AssociationKey.CornerRadius)  as? NSNumber ?? 0
      return (corners: UIRectCorner(rawValue: number.unsignedLongValue), radius: CGFloat(radius.floatValue))
    }
    set (v) {
      let radius = v.radius
      let closure:((Void)->Void) = {
        let path = UIBezierPath(roundedRect: self.bounds, byRoundingCorners: v.corners, cornerRadii: CGSize(width: radius, height: radius))
        let mask = CAShapeLayer()
        mask.path = path.CGPath
        self.mask = mask
      }
      let block: @convention(block) Void -> Void = closure
      let objectBlock = unsafeBitCast(block, AnyObject.self)
      objc_setAssociatedObject(self, &AssociationKey.CornerRect, NSNumber(unsignedLong: v.corners.rawValue), .OBJC_ASSOCIATION_RETAIN)
      objc_setAssociatedObject(self, &AssociationKey.CornerRadius, NSNumber(float: Float(v.radius)), .OBJC_ASSOCIATION_RETAIN)
      do { try aspect_hookSelector("layoutSublayers", withOptions: .PositionAfter, usingBlock: objectBlock) }
      catch _ { }
    }
  }
}

I wrote a simple blog post explaining this.

Answer 6

Swift 4 Easy Way in 1 line

Usage
//MARK:- Corner Radius of only two side of UIViews
    self.roundCorners(view: yourview, corners: [.bottomLeft, .topRight], radius: 12.0)

Functin
//MARK:- Corner Radius of only two side of UIViews
func roundCorners(view :UIView, corners: UIRectCorner, radius: CGFloat){
        let path = UIBezierPath(roundedRect: view.bounds, byRoundingCorners: corners, cornerRadii: CGSize(width: radius, height: radius))
        let mask = CAShapeLayer()
        mask.path = path.cgPath
        view.layer.mask = mask
}