iOS Why do NSTextAttachment disappear when setting NSBaselineOffsetAttributeName?

Question

I want to align the NSTextAttachment to the center of the text, so I set NSBaselineOffsetAttributeName

Answer 1

I finally solve it by adding another attribute NSParagraphStyleAttributeName

    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    paragraphStyle.minimumLineHeight = lineheight; //line height equals to image height
    [attributes setValue:paragraphStyle forKey:NSParagraphStyleAttributeName];

don't change the image's offset, just set the text's offset.