像Mail.app回复视图中的UITextView

Question

在iOS Mail应用中，当您点击回复时，会看到一个像这样的文本视图。当您尝试在进行内联回复时编辑上一个回复时，垂直蓝线会继续增长或缩小（视情况而定）。顶部（您的主要回复）看起来很正常。关于如何拉开这种文本视图的真正顶级的想法？

Answer 1

    textViewHolder = [[UIView alloc]initWithFrame:CGRectMake(20, 100, 280, 20)];
    simpleLine = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 2, 20)];
    simpleLine.backgroundColor = [UIColor blueColor];
    [textViewHolder addSubview:simpleLine];

    myTextView = [[UITextView alloc]initWithFrame:CGRectMake(20, 0, 240, 24)];
    myTextView.delegate = self;
    [textViewHolder addSubview:myTextView];
    [self.view addSubview:textViewHolder];


- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text;
{
    int numLines = myTextView.contentSize.height / myTextView.font.lineHeight;
    if([text isEqualToString:@"\n"])
        numLines++;

    if(numLines>1)
    {
        CGRect frame = textViewHolder.frame;
        frame.size.height = 20*(numLines-1);
        textViewHolder.frame =frame;

        CGRect frame2 = simpleLine.frame;
        frame2.size.height = 20*(numLines-1);
        simpleLine.frame =frame2;

        CGRect frame3 = myTextView.frame;
        frame3.size.height = 24*(numLines-1);
        myTextView.frame =frame3;
    }
    return YES;
}

(numLines-1)是因为我总是得到一条我需要的线。我确信它可以通过一些调试来解决。

[text isEqualToString:@"\n"]部分是因为如果用户按下完成并按下一行，您还希望增加行号。