在Xcode 6上 你试一试

     self.layer.layer.cornerRadius = 5.0f;

or

    self.layer.layer.cornerRadius = 5.0f;
    self.layer.clipsToBounds = YES;

你可以使用下面的自定义UIView类，它也可以改变边框颜色和宽度。因为这是IBDesignalbe，你也可以在界面构建器中更改属性。

import UIKit

@IBDesignable public class RoundedView: UIView {

    @IBInspectable var borderColor: UIColor = UIColor.white {
        didSet {
            layer.borderColor = borderColor.cgColor
        }
    }

    @IBInspectable var borderWidth: CGFloat = 2.0 {
        didSet {
            layer.borderWidth = borderWidth
        }
    }

    @IBInspectable var cornerRadius: CGFloat = 0.0 {
        didSet {
            layer.cornerRadius = cornerRadius
        }
    }

}

正如在这篇博文中所描述的，这里有一个方法来圆角的UIView:

+(void)roundView:(UIView *)view onCorner:(UIRectCorner)rectCorner radius:(float)radius
{
    UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:view.bounds
                                                   byRoundingCorners:rectCorner
                                                         cornerRadii:CGSizeMake(radius, radius)];
    CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
    maskLayer.frame = view.bounds;
    maskLayer.path = maskPath.CGPath;
    [view.layer setMask:maskLayer];
    [maskLayer release];
}

最酷的部分是你可以选择你想要四舍五入的角。

在Xcode 6上 你试一试

     self.layer.layer.cornerRadius = 5.0f;

or

    self.layer.layer.cornerRadius = 5.0f;
    self.layer.clipsToBounds = YES;

UIView* viewWithRoundedCornersSize(float cornerRadius,UIView * original)
{
    // Create a white border with defined width
    original.layer.borderColor = [UIColor yellowColor].CGColor;
    original.layer.borderWidth = 1.5;

    // Set image corner radius
    original.layer.cornerRadius =cornerRadius;

    // To enable corners to be "clipped"
    [original setClipsToBounds:YES];
    return original;
}

view.layer.cornerRadius = 25
view.layer.masksToBounds = true