Objective-C

#import <Foundation/Foundation.h>

@interface OTSCorner : NSObject

/**
 *   給 UIView 某幾個角添加圓角
 *
 *  @param aView    輸入view
 *  @param aCorners 要添加圓角的角（方向）
 *  @param aSize    圓角size
 */

+ (void)addCornerWithView:(UIView *)aView type:(UIRectCorner)aCorners size:(CGSize)aSize;

@end

#import "OTSCorner.h"

@implementation OTSCorner

+ (void)addCornerWithView:(UIView *)aView type:(UIRectCorner)aCorners size:(CGSize)aSize
{
    // 根據(jù)矩形畫帶圓角的曲線
    UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:aView.bounds byRoundingCorners:aCorners cornerRadii:aSize];
    CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
    maskLayer.frame = aView.bounds;
    maskLayer.path = maskPath.CGPath;
    aView.layer.mask = maskLayer;
}

@end

Swift

import UIKit

class OTSCorner: NSObject {
    
    /**
     *   給 UIView 某幾個角添加圓角
     *
     *  @param aView    輸入view
     *  @param aCorners 要添加圓角的角（方向）
     *  @param aSize    圓角size
     */
    class func addCornerWithView(aView : UIView, aCorners : UIRectCorner, aSize : CGSize) ->Void
    {
        // 根據(jù)矩形畫帶圓角的曲線
        let maskPath = UIBezierPath.init(roundedRect: aView.bounds, byRoundingCorners: aCorners, cornerRadii: aSize)
        let maskLayer = CAShapeLayer()
        maskLayer.frame = aView.bounds
        maskLayer.path = maskPath.CGPath
        aView.layer.mask = maskLayer
    }
}

Swift 測試

        let view = UIView()
        view.frame = CGRectMake(100, 100, 100, 100)
        view.backgroundColor = UIColor.redColor()
        self.view.addSubview(view)
        OTSCorner.addCornerWithView(view, aCorners:[.TopLeft, .TopRight, .BottomLeft, .BottomRight], aSize: CGSizeMake(20, 20))

測試效果

D8592B7C-84C2-4BA5-ACAF-BDE3E08A2584.png