确定 UILabel 中有多少个字符被截断

Question

我有一个UILabel，我想确定UILabel 中有多少字符被截断。
使用下面的代码，我可以确定我的UILabel 是否只有 1 行

int numberOfTruncatedCharacter = 0;
NSString *text = @"Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s";

NSArray  *words = [text componentsSeparatedByString:@" "];
NSString *newStr = @"";
for (NSString *word in words) {
    NSString *statement = [NSString stringWithFormat:@"%@ %@",newStr, word];
    CGSize size = [statement sizeWithAttributes:@{NSFontAttributeName: self.aboutLabel.font}];

    if(size.width < self.aboutLabel.bounds.size.width){
        newStr = [NSString stringWithFormat:@"%@ %@",newStr, word];
    }else{
        numberOfTruncatedCharacter++;
    }
    NSLog(@"%@ | %f | %f",word,size.width,self.aboutLabel.bounds.size.width);
}
NSLog(@"number of truncated character = %d",numberOfTruncatedCharacter);

它工作正常，这是日志

2016-05-27 10:02:44.642 EarCrush[2284:42690] Lorem | 32.622070 | 355.000000
2016-05-27 10:02:44.642 EarCrush[2284:42690] Ipsum | 64.345703 | 355.000000
2016-05-27 10:02:44.642 EarCrush[2284:42690] is | 74.243164 | 355.000000
2016-05-27 10:02:44.643 EarCrush[2284:42690] simply | 107.138672 | 355.000000
2016-05-27 10:02:44.643 EarCrush[2284:42690] dummy | 145.644531 | 355.000000
2016-05-27 10:02:44.643 EarCrush[2284:42690] text | 165.952148 | 355.000000
2016-05-27 10:02:44.644 EarCrush[2284:42690] of | 177.978516 | 355.000000
2016-05-27 10:02:44.644 EarCrush[2284:42690] the | 195.854492 | 355.000000
2016-05-27 10:02:44.645 EarCrush[2284:42690] printing | 235.004883 | 355.000000
2016-05-27 10:02:44.646 EarCrush[2284:42690] and | 255.429688 | 355.000000
2016-05-27 10:02:44.647 EarCrush[2284:42690] typesetting | 309.921875 | 355.000000
2016-05-27 10:02:44.648 EarCrush[2284:42690] industry. | 353.134766 | 355.000000
2016-05-27 10:02:44.649 EarCrush[2284:42690] Lorem | 385.756836 | 355.000000
2016-05-27 10:02:44.649 EarCrush[2284:42690] Ipsum | 384.858398 | 355.000000
2016-05-27 10:02:44.650 EarCrush[2284:42690] has | 372.202148 | 355.000000
2016-05-27 10:02:44.650 EarCrush[2284:42690] been | 379.218750 | 355.000000
2016-05-27 10:02:44.650 EarCrush[2284:42690] the | 371.010742 | 355.000000
2016-05-27 10:02:44.651 EarCrush[2284:42690] industry's | 401.171875 | 355.000000
2016-05-27 10:02:44.651 EarCrush[2284:42690] standard | 397.431641 | 355.000000
2016-05-27 10:02:44.652 EarCrush[2284:42690] dummy | 391.640625 | 355.000000
2016-05-27 10:02:44.652 EarCrush[2284:42690] text | 373.442383 | 355.000000
2016-05-27 10:02:44.653 EarCrush[2284:42690] ever | 375.844727 | 355.000000
2016-05-27 10:02:44.653 EarCrush[2284:42690] since | 379.541016 | 355.000000
2016-05-27 10:02:44.653 EarCrush[2284:42690] the | 371.010742 | 355.000000
2016-05-27 10:02:44.654 EarCrush[2284:42690] 1500s | 383.374023 | 355.000000
2016-05-27 10:02:44.654 EarCrush[2284:42690] number of truncated character = 13

问题是当我的UILabel 有多行时，我将代码更改为

if(size.width < self.aboutLabel.bounds.size.width * numberOfLines){

但是它不会正确计算。我想也许当UILabel 有多行时，它会包含换行符

任何解决它的想法。任何帮助或建议将不胜感激。

Answer 1

您正在检查宽度，但您需要检查高度。

查看此开源代码，了解 TTTAttributedLabel 如何使用 CoreText 了解何时添加“...”字符。

https://github.com/TTTAttributedLabel/TTTAttributedLabel/blob/master/TTTAttributedLabel/TTTAttributedLabel.m

看drawframesetter:attributedstring:textrange:inrect:context:方法

你也可以改开源，暴露'...'的位置

Answer 2

你可以这样做，

- (void)viewDidLoad {

  [super viewDidLoad];
  UILabel *label1 = self.myLabel;


UIFont *font = label1.font;
NSString *text = @"This is the label text wich will be truncate!!";

CGRect label1Frame = label1.frame;

NSUInteger numberOfCharsInLabel1 = NSNotFound;

NSUInteger numberOfCharactersThatTruncated = NSNotFound;

for (int i = [text length]; i >= 0; i--) {
    NSString *substring = [text substringToIndex:i];
    NSAttributedString *attributedText = [[NSAttributedString alloc] initWithString:substring
                                                                         attributes:@{ NSFontAttributeName : font }];
    CGSize size = CGSizeMake(label1Frame.size.width, CGFLOAT_MAX);
    CGRect textFrame = [attributedText boundingRectWithSize:size
                                                    options:NSStringDrawingUsesLineFragmentOrigin
                                                    context:nil];

    if (CGRectGetHeight(textFrame) <= CGRectGetHeight(label1Frame)) {
        numberOfCharsInLabel1 = i;

        numberOfCharactersThatTruncated = [text length] - numberOfCharsInLabel1;
        break;
    }
}

if (numberOfCharsInLabel1 == NSNotFound) {
    // TODO: Handle this case.
}

 label1.text = [text substringToIndex:numberOfCharsInLabel1];  // If you want to set character that label only can accept without truncating

//OR


label1.text = text;  //set full text with truncating


NSLog(@"Number of Truncated Characters %d",numberOfCharactersThatTruncated);


// Do any additional setup after loading the view.
}

这里self.myLabel是引用标签的出口。

numberOfCharactersThatTruncated 是你的desired output。

这将返回标签中被截断的字符数。

这将返回完全截断的字符我的意思是如果您的字符串是 Hello there 并且标签能够显示 hell 那么结果应该是 7 但您会在标签中看到类似 h... 因为标签截断时显示三个点。因此，如果您想计算根本不显示的字符，则需要在最终输出中添加3，即

  numberOfCharactersThatTruncated = numberOfCharactersThatTruncated + 3;

更新：

我标签的框架是：(27,75,93,56)

我刚刚设置了top,leading,fixed height,fixed width 约束。

同样的代码就像魅力一样工作。

我认为你在数字符时犯了错误。空白应被视为一个字符。然后，如果您的标签显示三个点，则意味着这三个字符标签可以显示。

例如：你的字符串是：你好吗？

所以总字符是：12

现在，例如您的标签显示：如何...

这意味着它显示 8 个字符（包括 .（点））

所以，numberOfCharactersThatTruncated 将返回 4。

如果您认为how a 只是可见字符而不考虑.，那么您应该将3 添加到numberOfCharactersThatTruncated。

如果您只想显示适合标签的字符，请使用label1.text = [text substringToIndex:numberOfCharsInLabel1]; this。

它不会显示点。

干杯....:)