kCTSuperscriptAttributeName不支持使用下标和上标

I am using this code for displaying subscript and superscript in label but it not working.

我正在使用这段代码在label中显示下标和上标，但它不起作用。

I create a category for NSAttributedString.

我为NSAttributedString创建一个类别。

-(void)setSuperscript:(BOOL)isSuperscript range:(NSRange)range {
    [self removeAttribute:(NSString * )kCTSuperscriptAttributeName range:range]; // Work around for Apple leak
    [self addAttribute:(NSString*)kCTSuperscriptAttributeName value:[NSNumber numberWithInt:(isSuperscript?1:0)] range:range];
}
-(void)setSubscript:(BOOL)isSubscript range:(NSRange)range {
    [self removeAttribute:(NSString * )kCTSuperscriptAttributeName range:range]; // Work around for Apple leak
    [self addAttribute:(NSString*)kCTSuperscriptAttributeName value:[NSNumber numberWithInt:(isSubscript?-1:0)] range:range];
}

1 个解决方案

#1

The problem is that many fonts either do not define super- and subscript variants, or have some rather funky (speak wrong) metrics for it.

问题是，许多字体要么不定义超和下标变体，要么有一些相当时髦(说错了)的度量标准。

A possible workaround is to fake it, like with the method below (in a category on NSMutableAttributedString). It has some shortcomings though:

一种可能的解决方法是伪造它，就像下面的方法一样(在NSMutableAttributedString的一个类别中)。但它也有一些缺点:

The stroke width isn't perfect, especially for larger font sizes
笔划宽度并不完美，尤其是对于较大的字体
It is somewhat harder to undo
这有点难以撤销
The calculated size and offset may not be perfect for some fonts
计算的尺寸和偏移量可能不适合某些字体。

On the plus side this should work for all fonts, and if needed can be tweaked for specific purposes.

从好的方面来说，这应该适用于所有字体，如果需要，可以针对特定的目的进行调整。

- (void)fakeSuperOrSubScript:(BOOL)superscript
    range:(NSRange)range
    defaultFont:(NSFont *)defaultFont
{

    NSFontManager   *fm=[NSFontManager sharedFontManager];
    NSFont          *font=[self
        attribute:NSFontAttributeName
        atIndex:range.location
        effectiveRange:NULL
    ];

    if(!font) font=defaultFont;
    if(!font)
    {
        NSLog(@"ERROR: fakeSuperOrSubScript has no font to use!");

        return;
    }

    // Bolden font to adjust stroke width
    NSFont          *siFont=[fm convertWeight:YES ofFont:font];
    float           originalSize=[siFont pointSize];
    float           newSize=originalSize*3.0/4.0;
    float           blOffset=(superscript)?originalSize/2.0:-originalSize/4.0;

    siFont=[fm convertFont:siFont toSize:newSize];

    NSDictionary *attrs=@{
        NSFontAttributeName:            siFont,
        NSBaselineOffsetAttributeName:  @(blOffset),
    };

    [self addAttributes:attrs range:range];
}

#1