ios-改变button四个角的弧度

-(void)createTitleView{
    UIView * backview = [[UIView alloc]init];
    backview.frame =CGRectMake(87*kHeight, nav.frame.size.height/2-13*kHeight,  146*kWidth, 26*kHeight);
    backview.backgroundColor = WhiteColor;
    backview.layer.cornerRadius = 5.0;
    [nav addSubview:backview];

    _btn1 = [com createBtn:@"待接单" andFont:FontOfSize14 andTag:1 and:self action:@selector(pressTitleBtn:) andTitleColor:YellowColor andBorderColor:WhiteColor andBackgroundColor:WhiteColor];
    _btn1.selected = YES;
    _btn1.frame = CGRectMake(0,0, 73*kWidth, 26*kHeight);
    [backview addSubview:_btn1];
    UIBezierPath *maskPath1 = [UIBezierPath bezierPathWithRoundedRect:_btn1.bounds      byRoundingCorners:UIRectCornerBottomLeft | UIRectCornerTopLeft    cornerRadii:CGSizeMake(6.0, 6.0)];
    CAShapeLayer *maskLayer1 = [[CAShapeLayer alloc] init];
    maskLayer1.frame = _btn1.bounds;
    maskLayer1.path = maskPath1.CGPath;
    _btn1.layer.mask = maskLayer1;

    _btn2 = [com createBtn:@"已接单" andFont:FontOfSize14 andTag:2 and:self action:@selector(pressTitleBtn:) andTitleColor:WhiteColor andBorderColor:WhiteColor andBackgroundColor:YellowColor];
    _btn2.selected = NO;
    _btn2.frame = CGRectMake(73*kWidth,0, 72.73*kWidth, 26*kHeight);
    UIBezierPath *maskPath2 = [UIBezierPath bezierPathWithRoundedRect:_btn2.bounds      byRoundingCorners:UIRectCornerBottomRight | UIRectCornerTopRight    cornerRadii:CGSizeMake(6.7, 6.7)];
    CAShapeLayer *maskLayer2 = [[CAShapeLayer alloc] init];
    maskLayer2.frame = _btn2.bounds;
    maskLayer2.path = maskPath2.CGPath;
    _btn2.layer.mask = maskLayer2;
    [backview addSubview:_btn2];

}