iOS --- UILabel添加中划线和下划线

1.

    UILabel *lbl_oldPrice = [[UILabel alloc]initWithFrame:CGRectMake(100, 100, 200, 30)];
    lbl_oldPrice.font = [UIFont systemFontOfSize:14];
    lbl_oldPrice.backgroundColor = [UIColor greenColor];
    NSString *textStr = @"￥199";
  
    //中划线
    NSDictionary *attribtDic1 = @{NSStrikethroughStyleAttributeName: [NSNumber numberWithInteger:NSUnderlineStyleSingle]};
    NSMutableAttributedString *attribtStr1 = [[NSMutableAttributedString alloc]initWithString:textStr attributes:attribtDic1];
    lbl_oldPrice.attributedText = attribtStr1;
    
    // 下划线
    NSDictionary *attribtDic2 = @{NSUnderlineStyleAttributeName: [NSNumber numberWithInteger:NSUnderlineStyleSingle]};
    NSMutableAttributedString *attribtStr2 = [[NSMutableAttributedString alloc]initWithString:textStr attributes:attribtDic2];
    lbl_oldPrice.attributedText = attribtStr2;
    lbl_oldPrice.attributedText = attribtStr1;
    
    lbl_oldPrice.textColor = [UIColor grayColor];
    lbl_oldPrice.textAlignment = NSTextAlignmentLeft;
    [self.view addSubview:lbl_oldPrice];

2.

iOS10.3更新后，商城APP这样的UI：原价 “￥500 ” 类似Label设置的中划线突然失效了。
这可能是苹果系统的一个bug。
根本原因：UILabel上的文字只要包含有“中文”，富文本字符串的中划线就会失效，我们可通过以下两种方式解决。

第一种方式：人民币符号“¥”和“￥”，使用前面一个即可。

NSString *market = [NSString stringWithFormat:@"¥%@",@"500"];
NSMutableAttributedString *attributeMarket = [[NSMutableAttributedString alloc] initWithString:market];
[attributeMarket setAttributes:@{NSStrikethroughStyleAttributeName: [NSNumber numberWithInteger:NSUnderlineStyleSingle]} range:NSMakeRange(0,market.length)];

_marketLabel.attributedText = attributeMarket;

第二种方式：让富文本支持“中文”

增加一个富文本属性： NSBaselineOffsetAttributeName : @(NSUnderlineStyleSingle)

NSString *market = [NSString stringWithFormat:@"￥%@",@"500"];
NSMutableAttributedString *attributeMarket = [[NSMutableAttributedString alloc] initWithString:market];
[attributeMarket setAttributes:@{NSStrikethroughStyleAttributeName: [NSNumber numberWithInteger:NSUnderlineStyleSingle], NSBaselineOffsetAttributeName : @(NSUnderlineStyleSingle)} range:NSMakeRange(0,market.length)];

_marketLabel.attributedText = attributeMarket;