UITextView高度根据内容变化

1.

添加内容变化的通知响应事件：

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name: UITextViewTextDidChangeNotification object:nil];

2 实现方法

- (void)textChanged:(NSNotification *)notification{
    
        if (self.textView.contentSize.height>45) {
            
            CGFloat textViewHeight=self.textView.contentSize.height;
            
            NSDictionary *dict =[[NSDictionary alloc]
                                 initWithObjectsAndKeys:@(textViewHeight+ViewHeight),@"textOne",nil];
            [[NSNotificationCenter defaultCenter]postNotificationName:NotificationAttitudeHeight object:nil userInfo:dict];
        }else{
            
            //        CGFloat textViewHeight=self.textView.contentSize.height;
            
            NSDictionary *dict =[[NSDictionary alloc]
                                 initWithObjectsAndKeys:@(50),@"textOne",nil];
            [[NSNotificationCenter defaultCenter]postNotificationName:NotificationAttitudeHeight object:nil userInfo:dict];
        }
}

还有一个地方需要注意，当你清空输入框时(_textView.text=@"";)，不会自动触发textChanged:，你需要重写setText:方法来调用textChanged:。并且你清空textview后，你拿到的contentsize也不准确，所以还需要根据text是否为空来设定一个最小的高度。

调用setneedslayout