创建根据输入内容实时改变高度的UITextView

0.创建textView

// 下面这一段代码，笔者就不费口舌了，读者应该都看的懂，就是创建一个外观类似于UITextField的UITextView 

self.contentTextView = [[UITextView alloc]initWithFrame:CGRectMake((kMainBoundsWidth-250)/2, kMainBoundsHeight/2-50, 250, 39)];
self.contentTextView .layer.cornerRadius = 4;
self.contentTextView .layer.masksToBounds = YES; self.contentTextView .delegate = self;
self.contentTextView .layer.borderWidth = 1; 
self.contentTextView .font = [UIFont systemFontOfSize:14]; self.contentTextView .layer.borderColor = [[[UIColor lightGrayColor] colorWithAlphaComponent:0.4] CGColor];
 //加下面一句话的目的是，是为了调整光标的位置，让光标出现在UITextView的正中间 
self.contentTextView.textContainerInset = UIEdgeInsetsMake(10,0, 0, 0); 
[self.view addSubview:self.contentTextView ];

1.计算输入文字高度的方法,之所以返回的高度值加22是因为UITextView有一个初始的高度值40，但是输入第一行文字的时候文字高度只有18，所以UITextView的高度会发生变化，效果不太好

- (float) heightForTextView: (UITextView *)textView WithText: (NSString *) strText{ 
CGSize constraint = CGSizeMake(textView.contentSize.width , CGFLOAT_MAX);
 CGRect size = [strText boundingRectWithSize:constraint options:(NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading) 
                attributes:@{NSFontAttributeName: [UIFont systemFontOfSize:14]} 
                context:nil];
 float textHeight = size.size.height + 22.0; return textHeight;
}

2.代理实现

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{ 

  CGRect frame = textView.frame; 
  float height; 

  if ([text isEqual:@""]) {
    if (![textView.text isEqualToString:@""]) {
      height = [ self heightForTextView:textView WithText:[textView.text substringToIndex:[textView.text length] - 1]];
    }else{ 
      height = [ self heightForTextView:textView WithText:textView.text]; 
    } 
  }else{
    height = [self heightForTextView:textView WithText:[NSString stringWithFormat:@"%@%@",textView.text,text]]; 
  }

  frame.size.height = height; 

  [UIView animateWithDuration:0.5 animations:^{ 
    textView.frame = frame; 
  } completion:nil]; 
  return YES;
}