UITextView自適應高度

currentLineNum = 1;//默認文本框顯示一行文字
NSDictionary *dict=@{NSFontAttributeName:[UIFont systemFontOfSize:14.0]};
CGSize contentSize=[@"我" sizeWithAttributes:dict];
heightText = contentSize.height;

self.textView.font = [UIFont systemFontOfSize:14.0];
self.textView.textContainerInset = UIEdgeInsetsZero;
self.textView.textContainer.lineFragmentPadding = 0;
self.textView.delegate = self;

#pragma mark - UITextViewDelegate
- (void)textViewDidChange:(UITextView *)textView{
    float textViewWidth = self.textView.frame.size.width;//取得文本框高度
    NSString *content = textView.text;
    NSDictionary *dict = @{NSFontAttributeName:[UIFont systemFontOfSize:14.0]};
    CGSize contentSize = [content sizeWithAttributes:dict];//計算文字長度
    float numLine = ceilf(contentSize.width/textViewWidth);
    if(numLine > currentLineNum ){
        //如果發現當前文字長度對應的行數超過。 文本框高度，則先調整當前view的高度和位置，然後調整輸入框的高度，最後修改currentLineNum的值
        self.layoutViewTextHeight.constant = self.textView.frame.size.height+heightText*(numLine-currentLineNum) + 28.0;
        currentLineNum = numLine;

   }else if (numLine < currentLineNum ){
       //次數爲刪除的時候檢測文字行數減少的時候
       if (numLine <= 1) {
           self.layoutViewTextHeight.constant = 48.0;
       }else {
           self.layoutViewTextHeight.constant = self.textView.frame.size.height-heightText*(currentLineNum-numLine) + 28.0;
       }
    }
    
    if (numLine == 0) {
        numLine = 1;
    }
    currentLineNum = numLine;
}

- (void)scrollViewDidScroll:(UIScrollView*)scrollView {
    // 防止換行時抖動
    scrollView.contentOffset = CGPointZero;
}