设置UIView几个角为圆角

   UIButton *btn = [[UIButton alloc] initWithFrame:CGRectMake(PhaseHalf(CGRectGetWidth(self.view.bounds),kWidth), PhaseHalf(CGRectGetHeight(self.view.bounds),kWidth), kWidth, kWidth)];

    [btn setBackgroundColor:[UIColor redColor]];

    [self.view addSubview:btn];

    [btn addTarget:self action:@selector(onBtnTouchUpInside:) forControlEvents:UIControlEventTouchUpInside];

    UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:btn.bounds byRoundingCorners:UIRectCornerBottomLeft| UIRectCornerBottomRight cornerRadii:CGSizeMake(10.0, 10.0)];

    CAShapeLayer *maskLayer = [CAShapeLayer layer];

    maskLayer.frame = btn.bounds;

    maskLayer.path = maskPath.CGPath;

    btn.layer.mask = maskLayer;