方法：

封装了以下方法，传入参数调整行间距

- (NSAttributedString *)getAttributedStringWithString:(NSString *)string lineSpace:(CGFloat)lineSpace {
    NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:string];
    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    paragraphStyle.lineSpacing = lineSpace;
    // 调整行间距
    NSRange range = NSMakeRange(0, [string length]);
    [attributedString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:range];
    return attributedString;
}

调用：

NSAttributedString *attstring = [self getAttributedStringWithString:@"12345678901234567890" lineSpace:3];
[_label setAttributedText:attstring];