可以使用UIBezierPath的
- (UIBezierPath *)bezierPathWithRoundedRect:(CGRect)rect
byRoundingCorners:(UIRectCorner)corners
cornerRadii:(CGSize)cornerRadii
參數(shù)corners指定了想要需要成為圓角的角致开』映常可選值為：
enum {
UIRectCornerTopLeft = 1 << 0,
UIRectCornerTopRight = 1 << 1,
UIRectCornerBottomLeft = 1 << 2,
UIRectCornerBottomRight = 1 << 3,
UIRectCornerAllCorners = ~0
};
typedef NSUInteger UIRectCorner;
從名字就能看出來其代表的意義。
例子：
UIView *view2 = [[UIView alloc] initWithFrame:CGRectMake(120, 10, 80, 80)];
view2.backgroundColor = [UIColor redColor];
[self.view addSubview:view2];
UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:view2.bounds byRoundingCorners:UIRectCornerBottomLeft | UIRectCornerBottomRight cornerRadii:CGSizeMake(10, 10)];
CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
maskLayer.frame = view2.bounds;
maskLayer.path = maskPath.CGPath;
view2.layer.mask = maskLayer;
如果需要將UIView的4個角全部都為圓角，做法相當簡單歼秽，只需設(shè)置其Layer的cornerRadius屬性即可。
