如何在NSAttributedString中控制图像和文本之间的填充？

Question

我使用NSTextAttachment在NSAttributedString中嵌入图像。但是我发现图像（PK图标）对文本是如此封闭，如果我想在它们之间做一些距离，如何实现这一点。

NSMutableAttributedString* attri = [[NSMutableAttributedString alloc] initWithString:[NSString stringWithFormat:@" %@",item.title]];
if (item.isPK)
{
    NSTextAttachment *imageAtta = [[NSTextAttachment alloc] init];
    imageAtta.bounds = CGRectMake(0, 0, 27, 13);
    imageAtta.image = [UIImage imageNamed:@"PKIcon"];
    NSAttributedString *attach = [NSAttributedString attributedStringWithAttachment:imageAtta];
    [attri insertAttributedString:attach atIndex:0];
}

self.titleLabel.attributedText = attri;