iOS CoreText CTLineGetStringRange with CTLineRef from CTLineCreateTruncatedLine

问题:

I have the following code in iOS:

CFAttributedStringRef attributedString = ... CTLineRef line = CTLineCreateWithAttributedString(attributedString); CTLineRef truncatedLine = CTLineCreateTruncatedLine(line, 50.0, kCTLineTruncationEnd, NULL);  CFRange lineRange = CTLineGetStringRange(line); CFRange truncatedLineRange = CTLineGetStringRange(truncatedLine); 

My lineRange is the same as truncatedLineRange. Why? The documentation makes no mention of this.

回答1:

According to the coretext-dev mailing list, this is expected behavior:

The truncated string still covers the original string range, it's just that some glyph(s) have subsumed the truncated characters. Besides, it would be impossible to represent a discontiguous string range as a CFRange in the case of middle truncation.

文章来源: iOS CoreText CTLineGetStringRange with CTLineRef from CTLineCreateTruncatedLine