直接上代码：
关键代码：
NSMutableAttributedString * attributedString = [[NSMutableAttributedString alloc] initWithString:lab.text];
NSMutableParagraphStyle * paragraphStyle = [[NSMutableParagraphStyle alloc] init];
[paragraphStylesetLineSpacing:8];
[attributedStringaddAttribute:NSParagraphStyleAttributeNamevalue:paragraphStylerange:NSMakeRange(0, [lab.textlength])];
[labsetAttributedText:attributedString];
