iOS调整字间距.行间距.换行

    UILabel *noticeLabel = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, 200, 100)];   
    noticeLabel.numberOfLines = 0;   // 系统默认为1,不加这行不能换行,不换行你就看不出效果
    NSString *str1 = @"扫描二维码\n关注中国政府网";
    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) :字间距缩进
    NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:text attributes:attributeDictionary];
    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    //调整行间距    
    paragraphStyle.maximumLineHeight = FontHeightTitle(46);
    paragraphStyle.minimumLineHeight = FontHeightTitle(46);
    [attributedString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, [text length])];
    return attributedString;
}