UILabel *noticeLabel = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, 200, 100)];   
    noticeLabel.numberOfLines = 0;   // 系統(tǒng)默認(rèn)為1,不加這行不能換行,不換行你就看不出效果
    NSString *str1 = @"掃描二維碼\n關(guān)注中國(guó)政府網(wǎng)";
    noticeLabel.attributedText = [self attributedStringOfTitleLabel:str1 withFont:[UIFont systemFontSize]];
    noticeLabel.textAlignment = NSTextAlignmentCenter;
    [self.view addSubview:noticeLabel];

- (NSMutableAttributedString *)attributedStringOfTitleLabel:(NSString *)text withFont:(UIFont *)font{
    NSDictionary *attributeDictionary = @{NSKernAttributeName : @(-1.0),NSFontAttributeName:font};  // NSKernAttributeName : @(-1.0) :字間距縮進(jìn)
    NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:text attributes:attributeDictionary];
    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    //調(diào)整行間距    
    paragraphStyle.maximumLineHeight = FontHeightTitle(46);
    paragraphStyle.minimumLineHeight = FontHeightTitle(46);
    [attributedString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, [text length])];
    return attributedString;
}