对于具有行间距和多种颜色的单行文本，UILabel 大小不正确

我很确定这实际上是一个 UIKit 错误，但想获得一些输入来看看我是否在这里遗漏了一些愚蠢的东西。

这是我的代码：

// 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];

以及一个简单的便利功能来改变lineSpacing属性字符串的：

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;
}

然而，这就是它的样子

正如您所看到的，第一个标签的高度太大（或者准确地说，它应该是的高度+我的自定义行间距）。当简单地向第一个属性字符串添加另一种颜色时，它会导致sizeToFit通过添加来增加尺寸lineSpacing在它下面。我也尝试使用boundingRectWithSize:直接在字符串上使用方法，同样的问题是可见的。因此，这不是特定于标签大小调整代码的，而是字符串本身的问题。我看不出有任何可能的原因会导致这种情况发生。有人有任何见解吗？

在你的属性字典中添加

 [attrDic setObject:@0 forKey:NSBaselineOffsetAttributeName];