只設置視圖的一個或幾個角爲圓角

可以使用
CAShapeLayer *styleLayer = [CAShapeLayerlayer];

UIBezierPath *shadowPath = [UIBezierPath bezierPathWithRoundedRect:cardStyleView.bounds byRoundingCorners:(UIRectCornerTopLeft|UIRectCornerTopRight) cornerRadii:CGSizeMake(8.0, 8.0)];

styleLayer.path = shadowPath.CGPath;

cardStyleView.layer.mask = styleLayer;
使用前需引用:頭文件：QuartzCore.FrameWork

文章鏈接:http://www.cnblogs.com/easonoutlook/archive/2012/12/10/2811363.html