Rounded UIView using CALayers - only some corners - How?
In iOS 11, we can now round some corners only
let view = UIView()
view.clipsToBounds = true
view.layer.cornerRadius = 8
view.layer.maskedCorners = [.layerMaxXMaxYCorner, .layerMinXMaxYCorner]
Starting in iOS 3.2, you can use the functionality of UIBezierPaths to create an out-of-the-box rounded rect (where only corners you specify are rounded). You can then use this as the path of a CAShapeLayer, and use this as a mask for your view's layer:
// Create the path (with only the top-left corner rounded)
UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:imageView.bounds
byRoundingCorners:UIRectCornerTopLeft
cornerRadii:CGSizeMake(10.0, 10.0)];
// Create the shape layer and set its path
CAShapeLayer *maskLayer = [CAShapeLayer layer];
maskLayer.frame = imageView.bounds;
maskLayer.path = maskPath.CGPath;
// Set the newly created shape layer as the mask for the image view's layer
imageView.layer.mask = maskLayer;
And that's it - no messing around manually defining shapes in Core Graphics, no creating masking images in Photoshop. The layer doesn't even need invalidating. Applying the rounded corner or changing to a new corner is as simple as defining a new UIBezierPath and using its CGPath as the mask layer's path. The corners parameter of the bezierPathWithRoundedRect:byRoundingCorners:cornerRadii: method is a bitmask, and so multiple corners can be rounded by ORing them together.
EDIT: Adding a shadow
If you're looking to add a shadow to this, a little more work is required.
Because "imageView.layer.mask = maskLayer" applies a mask, a shadow will not ordinarily show outside of it. The trick is to use a transparent view, and then add two sublayers (CALayers) to the view's layer: shadowLayer and roundedLayer. Both need to make use of the UIBezierPath. The image is added as the content of roundedLayer.
// Create a transparent view
UIView *theView = [[UIView alloc] initWithFrame:theFrame];
[theView setBackgroundColor:[UIColor clearColor]];
// Create the path (with only the top-left corner rounded)
UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:theView.bounds
byRoundingCorners:UIRectCornerTopLeft
cornerRadii:CGSizeMake(10.0f, 10.0f)];
// Create the shadow layer
CAShapeLayer *shadowLayer = [CAShapeLayer layer];
[shadowLayer setFrame:theView.bounds];
[shadowLayer setMasksToBounds:NO];
[shadowLayer setShadowPath:maskPath.CGPath];
// ...
// Set the shadowColor, shadowOffset, shadowOpacity & shadowRadius as required
// ...
// Create the rounded layer, and mask it using the rounded mask layer
CALayer *roundedLayer = [CALayer layer];
[roundedLayer setFrame:theView.bounds];
[roundedLayer setContents:(id)theImage.CGImage];
CAShapeLayer *maskLayer = [CAShapeLayer layer];
[maskLayer setFrame:theView.bounds];
[maskLayer setPath:maskPath.CGPath];
roundedLayer.mask = maskLayer;
// Add these two layers as sublayers to the view
[theView.layer addSublayer:shadowLayer];
[theView.layer addSublayer:roundedLayer];
I used the answer over at How do I create a round cornered UILabel on the iPhone? and the code from How is a rounded rect view with transparency done on iphone? to make this code.
Then I realized I'd answered the wrong question (gave a rounded UILabel instead of UIImage) so I used this code to change it:
http://discussions.apple.com/thread.jspa?threadID=1683876
Make an iPhone project with the View template. In the view controller, add this:
- (void)viewDidLoad
{
CGRect rect = CGRectMake(10, 10, 200, 100);
MyView *myView = [[MyView alloc] initWithFrame:rect];
[self.view addSubview:myView];
[super viewDidLoad];
}
MyView is just a UIImageView subclass:
@interface MyView : UIImageView
{
}
I'd never used graphics contexts before, but I managed to hobble together this code. It's missing the code for two of the corners. If you read the code, you can see how I implemented this (by deleting some of the CGContextAddArc calls, and deleting some of the radius values in the code. The code for all corners is there, so use that as a starting point and delete the parts that create corners you don't need. Note that you can make rectangles with 2 or 3 rounded corners too if you want.
The code's not perfect, but I'm sure you can tidy it up a little bit.
static void addRoundedRectToPath(CGContextRef context, CGRect rect, float radius, int roundedCornerPosition)
{
// all corners rounded
// CGContextMoveToPoint(context, rect.origin.x, rect.origin.y + radius);
// CGContextAddLineToPoint(context, rect.origin.x, rect.origin.y + rect.size.height - radius);
// CGContextAddArc(context, rect.origin.x + radius, rect.origin.y + rect.size.height - radius,
// radius, M_PI / 4, M_PI / 2, 1);
// CGContextAddLineToPoint(context, rect.origin.x + rect.size.width - radius,
// rect.origin.y + rect.size.height);
// CGContextAddArc(context, rect.origin.x + rect.size.width - radius,
// rect.origin.y + rect.size.height - radius, radius, M_PI / 2, 0.0f, 1);
// CGContextAddLineToPoint(context, rect.origin.x + rect.size.width, rect.origin.y + radius);
// CGContextAddArc(context, rect.origin.x + rect.size.width - radius, rect.origin.y + radius,
// radius, 0.0f, -M_PI / 2, 1);
// CGContextAddLineToPoint(context, rect.origin.x + radius, rect.origin.y);
// CGContextAddArc(context, rect.origin.x + radius, rect.origin.y + radius, radius,
// -M_PI / 2, M_PI, 1);
// top left
if (roundedCornerPosition == 1) {
CGContextMoveToPoint(context, rect.origin.x, rect.origin.y + radius);
CGContextAddLineToPoint(context, rect.origin.x, rect.origin.y + rect.size.height - radius);
CGContextAddArc(context, rect.origin.x + radius, rect.origin.y + rect.size.height - radius,
radius, M_PI / 4, M_PI / 2, 1);
CGContextAddLineToPoint(context, rect.origin.x + rect.size.width,
rect.origin.y + rect.size.height);
CGContextAddLineToPoint(context, rect.origin.x + rect.size.width, rect.origin.y);
CGContextAddLineToPoint(context, rect.origin.x, rect.origin.y);
}
// bottom left
if (roundedCornerPosition == 2) {
CGContextMoveToPoint(context, rect.origin.x, rect.origin.y);
CGContextAddLineToPoint(context, rect.origin.x, rect.origin.y + rect.size.height);
CGContextAddLineToPoint(context, rect.origin.x + rect.size.width,
rect.origin.y + rect.size.height);
CGContextAddLineToPoint(context, rect.origin.x + rect.size.width, rect.origin.y);
CGContextAddLineToPoint(context, rect.origin.x + radius, rect.origin.y);
CGContextAddArc(context, rect.origin.x + radius, rect.origin.y + radius, radius,
-M_PI / 2, M_PI, 1);
}
// add the other corners here
CGContextClosePath(context);
CGContextRestoreGState(context);
}
-(UIImage *)setImage
{
UIImage *img = [UIImage imageNamed:@"my_image.png"];
int w = img.size.width;
int h = img.size.height;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace, kCGImageAlphaPremultipliedFirst);
CGContextBeginPath(context);
CGRect rect = CGRectMake(0, 0, w, h);
addRoundedRectToPath(context, rect, 50, 1);
CGContextClosePath(context);
CGContextClip(context);
CGContextDrawImage(context, rect, img.CGImage);
CGImageRef imageMasked = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
[img release];
return [UIImage imageWithCGImage:imageMasked];
}
alt text http://nevan.net/skitch/skitched-20100224-092237.png
Don't forget that you'll need to get the QuartzCore framework in there for this to work.
I have used this code in many places in my code and it works 100% correctly. You can change any corder by changed one property "byRoundingCorners:UIRectCornerBottomLeft"
UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:view.bounds byRoundingCorners:UIRectCornerBottomLeft cornerRadii:CGSizeMake(10.0, 10.0)];
CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
maskLayer.frame = view.bounds;
maskLayer.path = maskPath.CGPath;
view.layer.mask = maskLayer;
[maskLayer release];