直接上代码

import <UIKit/UIKit.h>

define TEXTCOUNT @"TEXTCOUNT"

@interface EditTextView : UITextView

@property(nonatomic,strong)NSString * placeHolder; //占位文字
@property(nonatomic,strong)UIColor * textEditColor; //设置文本颜色
@property(nonatomic,strong)UIFont * fontEdit; //字体

@property(nonatomic, assign)CGFloat maxHeight; //textView最大高度设置，如果有，就设置，否则高度随着文字高度变化而变化

@property(nonatomic, assign)NSInteger textMaxCount; //设置最大输入文本个数

@property(nonatomic, assign)NSInteger textCount; //已经输入的文本个数,通过通知来获取

@end

import "EditTextView.h"

@interface EditTextView ()<UITextViewDelegate>

@property(nonatomic, assign)CGFloat width;

@property(nonatomic, assign)CGFloat height;

@end

@implementation EditTextView

• (instancetype)initWithFrame:(CGRect)frame{
  if (self = [super initWithFrame:frame]) {

    [self addObserver];
    self.textColor = [UIColor grayColor];
    self.delegate = self;
    self.width = CGRectGetWidth(self.frame);
    self.height = CGRectGetHeight(self.frame);
    self.showsVerticalScrollIndicator = NO;
  

  }
  return self;
  }

• (void)setFontEdit:(UIFont *)fontEdit{
  _fontEdit = fontEdit;
  self.font = fontEdit;
  }

• (void)setPlaceHolder:(NSString *)placeHolder{
  _placeHolder = placeHolder;
  self.text = placeHolder;
  }

• (void)addObserver{

  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textViewDidBeginEditing:) name:UITextViewTextDidBeginEditingNotification object:self];

  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textViewDidEndEditing:) name:UITextViewTextDidEndEditingNotification object:self];

  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textViewDidChange:) name:UITextViewTextDidChangeNotification object:self];
  }

• (void)textViewDidBeginEditing:(NSNotification *)notification{

  if ([[super text] isEqualToString:self.placeHolder]) {
  [super setText:@""];
  [super setTextColor:self.textEditColor];
  }
  }

• (void)textViewDidEndEditing:(NSNotification *)notification{

  if ([super text].length == 0) {
  [super setText:self.placeHolder];
  [super setTextColor: [UIColor grayColor]];
  }
  }

• (void)textViewDidChange:(NSNotification *)notification{

  NSString * textString = self.text;

//====================此处对输入字数限制
UITextRange *selectedRange = [self markedTextRange];
UITextPosition *position = [self positionFromPosition:selectedRange.start offset:0];

// 没有高亮选择的字，则对已输入的文字进行字数统计和限制,防止中文被截断
if (!position){
    if (self.textMaxCount&& textString.length > self.textMaxCount){
        NSRange rangeRange = [textString rangeOfComposedCharacterSequencesForRange:NSMakeRange(0, self.textMaxCount)];
        self.text = [textString substringWithRange:rangeRange];
    }
}

// 此处限制高度
CGRect rect = [textString boundingRectWithSize:CGSizeMake(self.width, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:self.fontEdit,NSForegroundColorAttributeName:self.textEditColor} context:nil];

CGRect newFrame = self.frame;
if (rect.size.height> self.height) {
    // 如果外部设置了固定高度
    if (self.maxHeight && rect.size.height> self.maxHeight) {
        newFrame.size = CGSizeMake(self.width, self.maxHeight);
    }else{
        newFrame.size = CGSizeMake(self.width, rect.size.height);
    }
}else{
    
    newFrame.size = CGSizeMake(self.width, self.height);
}


self.frame = newFrame;
self.textCount = self.text.length;
//发送通知，计算文本字数
[[NSNotificationCenter defaultCenter] postNotificationName:TEXTCOUNT object:@(self.textCount)];

}

//获取文本时，一定要排除占位符的情况

• (NSString *)text{
  if ([[super text] isEqualToString:self.placeHolder]) {
  return @"";
  }
  return [super text];
  }

• (void)dealloc{
  [[NSNotificationCenter defaultCenter] removeObserver:self];
  }

@end