UILabel大小不正确的单行文本与lineSpacing和多种颜色 [英] UILabel size incorrect for single line of text with lineSpacing and multiple colors

问题描述

我很确定这实际上是一个UIKit错误，但想要得到一些输入，看看我是否在这里失去了一些愚蠢。

I'm pretty sure this is actually a UIKit bug but want to get some input to see if I'm missing something silly here.

这里是代码我有：

// single line with modified line spacing and 2 colors - broken, line spacing is added to the bottom!
UILabel *brokenLabel = [[UILabel alloc] init];
brokenLabel.backgroundColor = [UIColor greenColor];

NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:@"Just some text"];

[attributedString addAttributes:@{NSForegroundColorAttributeName : [UIColor redColor]} range:[attributedString.string rangeOfString:@"text"]];

attributedString = attributedStringFromAttributedStringWithLineSpacing(attributedString, 20, NSTextAlignmentCenter);

brokenLabel.attributedText = attributedString;
[brokenLabel sizeToFit];
brokenLabel.frame = CGRectOffset(brokenLabel.frame, 50, 100);
[self.view addSubview:brokenLabel];
// end

// single line with modified line spacing and 1 color - correct
UILabel *workingLabel = [[UILabel alloc] init];
workingLabel.backgroundColor = [UIColor greenColor];

attributedString = [[NSMutableAttributedString alloc] initWithString:@"Just some text"];

attributedString = attributedStringFromAttributedStringWithLineSpacing(attributedString, 20, NSTextAlignmentCenter);

workingLabel.attributedText = attributedString;
[workingLabel sizeToFit];
workingLabel.frame = CGRectOffset(workingLabel.frame, 200, 100);
[self.view addSubview:workingLabel];
//end

// multiple lines with modified line spacing and 1 color - correct
UILabel *workingLabel2 = [[UILabel alloc] init];
workingLabel2.frame = CGRectMake(0, 0, 100, 0);
workingLabel2.numberOfLines = 0;
workingLabel2.backgroundColor = [UIColor greenColor];

attributedString = [[NSMutableAttributedString alloc] initWithString:@"Just some text"];

attributedString = attributedStringFromAttributedStringWithLineSpacing(attributedString, 20, NSTextAlignmentCenter);

workingLabel2.attributedText = attributedString;
[workingLabel2 sizeToFit];
workingLabel2.frame = CGRectOffset(workingLabel2.frame, 50, 300);
[self.view addSubview:workingLabel2];
//end

// multiple lines with modified line spacing and 2 color - correct
UILabel *workingLabel3 = [[UILabel alloc] init];
workingLabel3.frame = CGRectMake(0, 0, 100, 0);
workingLabel3.numberOfLines = 0;
workingLabel3.backgroundColor = [UIColor greenColor];

attributedString = [[NSMutableAttributedString alloc] initWithString:@"Just some text"];

[attributedString addAttributes:@{NSForegroundColorAttributeName : [UIColor redColor]} range:[attributedString.string rangeOfString:@"text"]];

attributedString = attributedStringFromAttributedStringWithLineSpacing(attributedString, 20, NSTextAlignmentCenter);

workingLabel3.attributedText = attributedString;
[workingLabel3 sizeToFit];
workingLabel3.frame = CGRectOffset(workingLabel3.frame, 200, 300);
[self.view addSubview:workingLabel3];

以及一个简单的方便功能来更改 lineSpacing 属性字符串：

along with a simple convenience function to change the lineSpacing of an attributed string:

NSMutableAttributedString *attributedStringFromAttributedStringWithLineSpacing(NSAttributedString *string, CGFloat lineSpacing, NSTextAlignment textAlignment)
{
    NSMutableAttributedString *mutable = string.mutableCopy;

    NSMutableParagraphStyle *par = [NSMutableParagraphStyle new];
    par.alignment = textAlignment;
    par.lineSpacing = lineSpacing;
    [mutable addAttributes:@{NSParagraphStyleAttributeName : par} range:NSMakeRange(0, mutable.length)];
    return mutable;
}

但是，这是什么样子

你可以看到，第一个标签的高度太大（或高度，它应该是+我的自定义行距，要精确）。当简单地向第一个属性字符串添加另一种颜色时，通过在下面添加 lineSpacing ，使 sizeToFit 。我也尝试直接使用 boundingRectWithSize：方法，同样的问题是可见的。所以这不是特定于标签大小调整代码，但是字符串本身的问题。我没有看到任何可能的原因，为什么这应该发生。

As you can see, the height of the first label is way too big (or the height that it should be + my custom line spacing, to be precise). When simply adding another color to the first attributed string, it causes the sizeToFit size to increase by adding the lineSpacing below it. I also tried using the boundingRectWithSize: methods on the strings directly and the same issue is visible. So this is not specific to the label sizing code but is an issue with the strings themselves. I don't see any possible reason why this should be happening. Does anyone have any insight?

推荐答案

在您的属性字典中添加

 [attrDic setObject:@0 forKey:NSBaselineOffsetAttributeName];

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