ios - sizeWithFont:constrainedToSize: 不计算 NSString 中的 "\n"

Question

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
    NSString *substring = textView.text;
    substring = (text.length == 0 && range.length == 1) ?
    [substring substringToIndex: substring.length-1] : [substring stringByAppendingString: text];

    CGSize size = [substring sizeWithFont:textView.font
                        constrainedToSize:CGSizeMake(textView.frame.size.width, 200.0)];

    CGFloat height = MAX(size.height, firstHeight);

    if(height != lastHeight)
    {
        CGFloat y = height - lastHeight;
        CHANGE_HEIGHT(textView, height);
        lastHeight = height;
    }   
    return YES;
}

问题是这sizeWithFont:constrainedToSize:给了我错误的高度。例如，如果文本是" Hello \n" sizeWithFont将不计入" \n"，因此"Hello"和" Hello \n"文本的高度相同。

任何需要的帮助将不胜感激！

Answer 1

无关，但你得到你的方式substring是忽略文本被修改的范围。

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
    NSString *textToMeasure = [textView.text stringByReplacingCharactersInRange:range withString:text];
    if ([textToMeasure hasSuffix:@"\n"]) {
        textToMeasure = [NSString stringWithFormat:@"%@-", textView.text];
    ...
}