UILabel设定行间距方法

NSString *textStr = @"iPhone规定：任何应用想访问麦克风，必须被授权麦克风服务。请进入“设置”->“隐私”->“麦克风”中打开QQ空间的麦克风服务。";
UIFont *textFont = [UIFont systemFontOfSize:14];
CGSize textSize = [textStr sizeWithFont:textFont
constrainedToSize:CGSizeMake(bounds.size.width - 40, QZONE_SCREEN_HEIGHT)];;
UILabel *openMicPrivilegeTipsLabel = [[UILabel alloc] initWithFrame:CGRectMake(20, 20, textSize.width, textSize.height)];
openMicPrivilegeTipsLabel.textColor = DefaultDescriptionText2ColorInDefaultTheme;
openMicPrivilegeTipsLabel.text = textStr;
openMicPrivilegeTipsLabel.backgroundColor = [UIColor clearColor];
openMicPrivilegeTipsLabel.textAlignment = UITextAlignmentLeft;
openMicPrivilegeTipsLabel.font = [UIFont systemFontOfSize:14];
openMicPrivilegeTipsLabel.numberOfLines = 0;

// 调整行间距
NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:textStr];
NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
[paragraphStyle setLineSpacing:6];
[attributedString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, [textStr length])];
openMicPrivilegeTipsLabel.attributedText = attributedString;

[_tipsBG addSubview:openMicPrivilegeTipsLabel];
[openMicPrivilegeTipsLabel sizeToFit];