iOS + 根据UITextView获取任一字符位置、末尾字符位

需求：设置标题，最多显示两行，多余的字符串以"..."截断，并在标题末尾追加编辑按钮

1. 获取UITextView中任一字符位置

    - (CGRect)rectOfCharacterAtIndex:(NSInteger)index inTextView:(UITextView *)textView {
        if (!textView) {
            return CGRectZero;
        }
       
        NSString *text = textView.text;
        if (index <= 0 && index >= text.length) {
            return CGRectZero;
        }
        
        // 获取每个字符的位置
        [textView setSelectedRange:NSMakeRange(index,1)];
        NSArray<UITextSelectionRect *> *rects = [textView selectionRectsForRange:textView.selectedTextRange];
        [textView setSelectedRange:NSMakeRange(0, 0)];
        
        // 获取字符有效的位置
        CGRect charRect = rects.firstObject.rect;
        for (UITextSelectionRect *rect in rects) {
            // rect有效的情况下
            if (rect.rect.size.width > 0 && rect.rect.size.height > 0) {
                if (CGRectGetMinY(charRect) <  CGRectGetMinY(rect.rect)) {
                    charRect = rect.rect;
                } else if (CGRectGetMinY(charRect) == CGRectGetMinY(rect.rect) && CGRectGetMinX(charRect) < CGRectGetMinX(rect.rect)) {
                    charRect = rect.rect;
                }
            }
        }
   
        return charRect;
    }
   

2. 获取每一行字符串的长度及该行最后一个字符下标

    // 计算每一行的rect及最后一个字符的下标
    - (NSArray *)lineInformaitonOfTextView:(UITextView *)textView {
        NSString *text = textView.text;
        NSMutableDictionary<NSString *, NSDictionary *> *lineInfo = [NSMutableDictionary dictionary];
        for (NSInteger index = 0; index < text.length; index++) {
            CGRect charRect = [self rectOfCharacterAtIndex:index inTextView:textView];
            NSString *YKey = [NSString stringWithFormat:@"%.0f", charRect.origin.y];
            NSMutableDictionary *info = [lineInfo[YKey] mutableCopy];
            if (!info) {
                info = [NSMutableDictionary dictionary];
            }
            
            info[@"lastCharIndex"] = @(index);
            
            if (!info[@"rect"]) {
                info[@"rect"] = [NSValue valueWithCGRect:charRect];
            } else {
                CGRect rect = [info[@"rect"] CGRectValue];
                if (rect.origin.x > charRect.origin.x) {
                    rect.origin.x = charRect.origin.x;
                }
                if (rect.origin.y > charRect.origin.y) {
                    rect.origin.y = charRect.origin.y; 
                }
                if (CGRectGetMaxX(rect) < CGRectGetMaxX(charRect)) {
                    rect.size.width = CGRectGetMaxX(charRect) - CGRectGetMinX(rect);
                }
                if (CGRectGetMaxY(rect) < CGRectGetMaxY(charRect)) {
                    rect.size.height = CGRectGetMaxY(charRect) - CGRectGetMinY(rect); 
                }
                info[@"rect"] = [NSValue valueWithCGRect:rect];
            }
            lineInfo[YKey] = info;
        }
        
        // 对行排序
        NSMutableArray *allYValue = [lineInfo.allKeys mutableCopy];
        [allYValue sortUsingComparator:^NSComparisonResult(NSString *obj1, NSString *obj2) {
            if (obj1.integerValue <= obj2.integerValue) {
                return NSOrderedAscending;
            } else {
                return NSOrderedDescending;
            }
        }];
        
        // 按行顺序返回数据
        NSMutableArray *lineArray = [NSMutableArray array];
        for (NSString *lineKey in allYValue) {
            [lineArray addObject:lineInfo[lineKey]];
        }
        return lineArray;
    }
   

3. 限制行数、及限制最后一行的长度

    /** 限制行数且以...在末尾截断，最后一行末尾空出间隔追加控件
     * @param numberOfLine 限制行数
     * @param appendLength 最后一行的末尾空白区
    */
    - (void)setString:(NSString *)string attributes:(NSDictionary *)attributes textView:(UITextView *)textView maxNumberOfLine:(NSInteger)numberOfLine appendLength:(CGFloat)appendLength {
        if (!textView) {
            return ;
        }
        
        // 设置字符串
        string = [string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
        textView.text = string;
        if (attributes && string) {
            textView.text = nil;
            NSMutableAttributedString *attributeString = [[NSMutableAttributedString alloc] initWithString:string attributes:attributes];
            textView.attributedText = attributeString;
        }
        CGRect textFrame = textView.frame;
        textFrame.size.height = [textView sizeThatFits:CGSizeMake(textFrame.size.width, MAXFLOAT)].height;
        textView.frame = textFrame;
        
        // 获取每一行字符串位置
        NSArray *lineInfoArray = [self lineInformaitonOfTextView:textView];
        
        // 当行号等于或超过限制行数时，需调整最后一行的字符，以便能空出appendLength的位置
        if (lineInfoArray.count >= numberOfLine) {
            NSDictionary *lineInfo = lineInfoArray[numberOfLine - 1];
            CGFloat adjustLastLineLength = CGRectGetMaxX([lineInfo[@"rect"] CGRectValue]); // 调整过后，最后一行字符的宽度
            NSInteger adjustIndex = [lineInfo[@"lastCharIndex"] integerValue]; // 调整过后，字符开始截断的位置
            // 最后一行的空余位置不够appendLength时，才需要偏移
            if (adjustIndex > 0 && adjustLastLineLength + appendLength > textFrame.size.width) {
                // 偏移下标，空出appendLength的位置
                for (; adjustIndex > 0; adjustIndex--) {
                    CGRect charRect = [self rectOfCharacterAtIndex:adjustIndex inTextView:textView];
                    if (CGRectGetMinX(charRect) + appendLength < textFrame.size.width) {
                        break;
                    }
                }
                
                // 截断字符串
                NSString *adjustText = textView.text;
                if (adjustIndex >= 0 && adjustIndex < adjustText.length) {
                    adjustText = [adjustText stringByReplacingCharactersInRange:NSMakeRange(adjustIndex, adjustText.length - adjustIndex) withString:@"..."];
                    // 重新设置值
                    textView.text = adjustText;
                    if (attributes && adjustText) {
                        textView.text = nil;
                        NSMutableAttributedString *attributeString = [[NSMutableAttributedString alloc] initWithString:adjustText attributes:attributes];
                        textView.attributedText = attributeString;
                    }
                }
            }
        }
        
        textFrame.size.height = [textView sizeThatFits:CGSizeMake(textFrame.size.width, MAXFLOAT)].height;
        textView.frame = textFrame;
    }