使用NSTextAttachment为NSAttributedString设置截断尾部的垂直对齐

Question

我正在使用以下代码在iOS 8中为NSAttributedString生成UILabel。

// a long long Chinese title 
NSString *title = @"这是一个很长很长很长很长很长很长的中文标题";
// setup icon attachment
NSTextAttachment *iconAttachment = [[NSTextAttachment alloc] init];
iconAttachment.image = [UIImage imageNamed:imageName];
iconAttachment.bounds = bounds;
NSAttributedString *ycardImageString = [NSAttributedString attributedStringWithAttachment:iconAttachment];

// setup attributed text
NSMutableAttributedString *attributedText = [[NSMutableAttributedString alloc] initWithString:title];
if (shouldShowYcard) {
    [attributedText insertAttributedString:ycardImageString atIndex:0];
    [attributedText insertAttributedString:[[NSAttributedString alloc] initWithString:@" "] atIndex:1];
    [attributedText addAttribute:NSBaselineOffsetAttributeName value:@(offset) range:NSMakeRange(0, 1)];
}
NSRange titleRange = NSMakeRange(shouldShowYcard ? 2 : 0, title.length);
[attributedText addAttribute:NSFontAttributeName value:font range:titleRange];
[attributedText addAttribute:NSForegroundColorAttributeName value:color range:titleRange];

然而，似乎NSTextAttachment会影响截断尾部的垂直位置，就像下面的图片一样。

有没有办法为截断的尾部设置垂直对齐？

我的目标是用中文底部对齐尾部。

这是测试的图标。

Answer 1

试试这个

   UILabel *lbl = [[UILabel alloc]initWithFrame:CGRectMake(50, 300, 300, 30)];
    [self.view addSubview:lbl];
    NSString *t= @"这是一个很长很长很长很长很长很长的中文标题漢字";
    NSTextAttachment *iconatt = [[NSTextAttachment alloc]init];
    iconatt.image = [UIImage imageNamed:@"phnzY.png"];
    iconatt.bounds = CGRectMake(0, 0, 44, 22);

    NSAttributedString *ycardstring = [NSAttributedString attributedStringWithAttachment:iconatt];
    NSMutableAttributedString *attributedText = [[NSMutableAttributedString alloc] initWithString:t];
    [attributedText insertAttributedString:ycardstring atIndex:0];
    [attributedText insertAttributedString:[[NSAttributedString alloc] initWithString:@" "] atIndex:1];
     [attributedText addAttribute:NSBaselineOffsetAttributeName value:@(0.0) range:NSMakeRange(0, 1)];
        NSRange titleRange = NSMakeRange( 0 , t.length);
    [attributedText addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:22.0] range:titleRange];
    [attributedText addAttribute:NSForegroundColorAttributeName value:[UIColor blackColor] range:titleRange];
    lbl.attributedText = attributedText;

它会像这样输出

Answer 2

您可以尝试使用NSMutableParagraphStyle来设置paragraphStyle。 这是代码：

    let label1 = UILabel(frame: CGRect(x: 50, y: 50, width: 100, height: 30))
    let label2 = UILabel(frame: CGRect(x: 50, y: 90, width: 100, height: 30))
    view.addSubview(label1)
    view.addSubview(label2)
    let t = "12341421dsadyusatdiuwtquyidtywatyudigsaydgsadysaghdkgaugduiyyudgasgdj"
    let iconAttachment = NSTextAttachment()
    iconAttachment.image = UIImage(named: "caseEditorBtn0")
    iconAttachment.bounds = CGRect(x: 0, y: 0, width: 20, height: 30);
    let ycardImageString = NSAttributedString(attachment: iconAttachment)
    let yT0 = NSMutableAttributedString(string: t)
    let yT1 = NSMutableAttributedString(string: t)

    let p = NSMutableParagraphStyle()
    p.lineBreakMode = .byTruncatingTail //set line break model
    p.alignment = .right                //set aligment
    yT1.setAttributes([NSParagraphStyleAttributeName: p], range: NSRange(location: 0, length: yT1.length))
    yT0.setAttributes([NSParagraphStyleAttributeName: p], range: NSRange(location: 0, length: yT0.length))
    //insert you custom text attachment at last, or it may be not show
    yT0.insert(ycardImageString, at: 0) 

    label1.attributedText =  yT0
    label2.attributedText = yT1

Answer 3

好的，最后我选择了一种丑陋的方法来解决这个问题，方法是设置NSBaselineOffsetAttributeName for truncate tail。

Here是计算截断部分的一种方法。但在我的情况下，我的标签宽度是固定的，所以我可以直接设置控制范围。

if (title.length > 10 && ([[[UIDevice currentDevice] systemVersion] floatValue] < 9.0)) {
    [attributedText addAttribute:NSBaselineOffsetAttributeName value:@(-4) range:NSMakeRange(9, 1)];
}