ios - 获取核心文本中点击字符的索引

Question

我需要能够可靠地获取 Core Text 框架中点击字符的索引。我有这段代码，它可靠地得到了正确的行，但它在点击索引上从零到 2 个字符。错误总是向前的；也就是说，它在正确索引之前获取索引 1 到 2 个字符。在长段的开头，通常会相差 2 个字符；到最后，它通常是正确的。我的文本是属性字符串中的希腊文本，不确定这是否有所不同。

如有任何帮助，我们将不胜感激。

谢谢。

- (void)receivedTap:(UITapGestureRecognizer*)recognizer
{
    CGAffineTransform transform = CGAffineTransformMake(1, 0, 0, -1, 0, self.bounds.size.height);
    CGPoint point = CGPointApplyAffineTransform([recognizer locationInView:self], transform);

    // Getting all CTLines
    CFArrayRef lines = CTFrameGetLines(textFrame);
    CFIndex countOfLines = CFArrayGetCount(lines);

    int lineNumber = 0;
    for ( CFIndex i = 0; i < countOfLines; i++ ) // For each CTLine
    {
        CTLineRef line = CFArrayGetValueAtIndex(lines, i);
        CGRect lineRect = CGRectZero;
        CGFloat ascent = 0, descent = 0;

        // Calculating CTLine frame 
        CTFrameGetLineOrigins(textFrame, CFRangeMake(i, 1), &lineRect.origin);
        lineRect.size.width = CTLineGetTypographicBounds(line, &ascent, &descent, NULL);
        lineRect.size.width -= CTLineGetTrailingWhitespaceWidth(line);
        lineRect.size.height = ascent + descent;
        lineRect.origin.y -= descent;
        lineRect = CGRectIntegral(lineRect);

        if ( ! CGRectContainsPoint(lineRect, point) ) {
            lineNumber++;
            continue; 
        }
        NSLog(@"line is %d", lineNumber);
        CFIndex touchedIndex = CTLineGetStringIndexForPosition(line, point);
        NSInteger touchedIndexInt = (NSInteger)touchedIndex;
        NSLog(@"found it : char %d", touchedIndexInt);
        break;
}

Answer 1

你试过把它放在 UITextView 中并做类似的事情吗

    UITextPosition *touchPosition = [self.textView closestPositionToPoint:point];
    UITextRange *touchRange = [self.textView.tokenizer rangeEnclosingPosition:touchPosition withGranularity:UITextGranularityCharacter inDirection:UITextLayoutDirectionRight];
    NSLog(@"%@",[self.textView textInRange: touchRange]);