在使用Masnory的同时，使用CAShapeLayer和UIB

今天在使用UIBezierPath给UIImageView设置任意圆角的时候发现图片不展示了，源码是这样的：

- (UIImageView *)imageV{
    if (!_imageV) {
        _imageV = [[UIImageView alloc]init];
        _imageV.contentMode = UIViewContentModeScaleAspectFill;
        UIBezierPath *rounded = [UIBezierPath bezierPathWithRoundedRect:_imageV.bounds byRoundingCorners:UIRectCornerTopRight | UIRectCornerTopLeft cornerRadii:CGSizeMake(3, 3)];
        CAShapeLayer *shape = [[CAShapeLayer alloc] init];
        [shape setPath:rounded.CGPath];
        _imageV.layer.mask = shape;
        _imageV.layer.masksToBounds = YES;
        _imageV.backgroundColor = [UIColor pq_whiteColor];
    }
    return _imageV;
}
[self.view addSubview:self.imageV];
    [self.imageV mas_makeConstraints:^(MASConstraintMaker *make) {
        make.top.left.mas_equalTo(15);
        make.width.mas_equalTo(kScreenWidth-30);
        make.height.mas_equalTo(kScreenWidth/2-15);
    }];

查看图层之后发现imageV的高度为0，原因是设置圆角的时候imageV的frame跟bounds都是0，所以在设置完约束条件之后需要这样做：

[self.imageV layoutIfNeeded];
UIBezierPath *rounded = [UIBezierPath bezierPathWithRoundedRect:_imageV.bounds byRoundingCorners:UIRectCornerTopRight | UIRectCornerTopLeft cornerRadii:CGSizeMake(3, 3)];
      CAShapeLayer *shape = [[CAShapeLayer alloc] init];
        [shape setPath:rounded.CGPath];
        self.imageV.layer.mask = shape;

问题解决！