史上最好用的UITextview子类

2017-04-13 本文已影响118人 laitys

gitDemo地址：https://github.com/laity1991/WKTextView

一.前言

之前做项目封装textView时存在一些bug一直未解决：文本信息在用户粘贴过长超出设定的最大字数时、带emoji时截取显示半个或乱码（因为emoji在iOS中使用的是UTF16也就是占位符是8+8两个字节的，占的长度为2,因此在计算字数时一个表情就占了2）

查了网上的一些封装demo，或是不太全或是存在一些小bug，在此我整理封装了一套WKTextView，方便大家使用和自己备用，主要解决问题：**
1.添加了占位文本，类似于textField的placeholder 　
2.中，英文字符输入时限制。
3.带emoji时截取显示半个或乱码字符处理。
4.处理了用户在粘贴过来文本超出字数限制存在bug的情况**

** 这里用到了我写的UIView的一个分类UIView+WKCategory (重写frame setter、getter方法)，注释比较详细，不做过多赘述**

二 .WKTextView源码

*** WKTextView.h ***

#import <UIKit/UIKit.h>
@interface WKTextView : UITextView
//文字
@property(nonatomic,copy) NSString *myPlaceholder;
//文字颜色
@property(nonatomic,strong) UIColor *myPlaceholderColor;
//最多输入字数
@property (nonatomic, assign) NSInteger maxNum;
///右下角统计字数label
@property (nonatomic, strong) UILabel *countLabel;
@end

*** WKTextView.m ***
#import "WKTextView.h"
#import "UIView+WKCategory.h"
@interface WKTextView()<UITextViewDelegate>
@property (nonatomic,weak) UILabel *placeholderLabel;
@end

@implementation WKTextView

 - (instancetype)initWithFrame:(CGRect)frame{
  self = [super initWithFrame:frame];
  if (self) {
  UILabel *placeholderLabel = [[UILabel alloc]init];
  [self addSubview:placeholderLabel];
  placeholderLabel.textColor = [UIColor lightGrayColor];
  self.placeholderLabel= placeholderLabel;
  UILabel *countLabel = [[UILabel alloc]init];
  [self addSubview:countLabel];
  countLabel.frame = CGRectMake(self.width - 60, self.height - 40, 60, 40);
  countLabel.textAlignment = NSTextAlignmentCenter;
  countLabel.textColor = [UIColor lightGrayColor];
  countLabel.text = @"0/100";
  self.countLabel = countLabel;
  ///设置边框
  self.layer.masksToBounds = YES;
  self.layer.cornerRadius = 4;
  self.layer.borderColor = [UIColor grayColor].CGColor;
  self.layer.borderWidth = 1;
  
  self.delegate = self;
  return self;
}
- (void)layoutSubviews{
    [super layoutSubviews];
    self.placeholderLabel.x = 8;
    self.placeholderLabel.y = 8;
    self.placeholderLabel.width = self.width - 
    2*self.placeholderLabel.x;
    ///根据占位文字myPlaceholder 算出占位Label的高度(宽度已定 高速自适应)
    CGSize maxSize = CGSizeMake(self.placeholderLabel.width, MAXFLOAT);
    self.placeholderLabel.height = [self.myPlaceholder boundingRectWithSize:maxSize 
    options:NSStringDrawingUsesFontLeading | NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:self.placeholderLabel.font} context:nil].size.height;
}

///箭头textView的输入文字变化 以此控制占位label的显示和隐藏
- (void)textDidChange{
   //hasText是UITextView的属性 如果textView输入了文字就是
   YES 没有文字就是NO
    self.placeholderLabel.hidden = self.hasText;

}

#pragma mark - UITextViewDelegate

- (BOOL)textView:(UITextView *)textView 
   shouldChangeTextInRange:(NSRange)range 
   replacementText:(NSString *)text{
   if ([text isEqualToString:@"\n"]) {
  [self resignFirstResponder];
  return NO;
 }
UITextRange *selectedRange = [textView markedTextRange];
//获取高亮部分
 UITextPosition *pos = [textView 
 positionFromPosition:selectedRange.start offset:0];
 //获取高亮部分内容
 //NSString * selectedtext = [textView 
 textInRange:selectedRange];

//如果有高亮且当前字数开始位置小于最大限制时允许输入
  if (selectedRange && pos) {
  NSInteger startOffset = [textView offsetFromPosition:textView.beginningOfDocument toPosition:selectedRange.start];
  NSInteger endOffset = [textView offsetFromPosition:textView.beginningOfDocument toPosition:selectedRange.end];
  NSRange offsetRange = NSMakeRange(startOffset, endOffset - startOffset);
  
  if (offsetRange.location < self.maxNum) {
      return YES;
  }
  else
  {
      return NO;
  }
 }
   NSString *comcatstr = [textView.text stringByReplacingCharactersInRange:range withString:text];

   NSInteger caninputlen = self.maxNum - comcatstr.length;

   if (caninputlen >= 0)
   {
  return YES;
    }
    else
    {
  NSInteger len = text.length + caninputlen;
  //防止当text.length + caninputlen < 0时，使得rg.length为一个非法最大正数出错
  NSRange rg = {0,MAX(len,0)};
  
  if (rg.length > 0)
  {
      NSString *s = @"";
      //判断是否只普通的字符或asc码(对于中文和表情返回NO)
      BOOL asc = [text canBeConvertedToEncoding:NSASCIIStringEncoding];
      if (asc) {
          s = [text substringWithRange:rg];//因为是ascii码直接取就可以了不会错
               }
      else
      {
          __block NSInteger idx = 0;
          __block NSString  *trimString = @"";//截取出的字串
          //使用字符串遍历，这个方法能准确知道每个emoji是占一个unicode还是两个
          [text enumerateSubstringsInRange:NSMakeRange(0, [text length])
                                   options:NSStringEnumerationByComposedCharacterSequences
                                usingBlock: ^(NSString* substring, NSRange substringRange, NSRange enclosingRange, BOOL* stop) {
                                    
                                    if (idx >= rg.length) {
                                        *stop = YES; //取出所需要就break，提高效率
                                        return ;
                                    }
                                    
                                    trimString = [trimString stringByAppendingString:substring];
                                    
                                    idx++;
                                }];
          
          s = trimString;
      }
      //rang是指从当前光标处进行替换处理(注意如果执行此句后面返回的是YES会触发didchange事件)
      [textView setText:[textView.text stringByReplacingCharactersInRange:range withString:s]];
      //既然是超出部分截取了，哪一定是最大限制了。
      self.countLabel.text = [NSString stringWithFormat:@"%ld/%ld",(long)self.maxNum,(long)self.maxNum];
      
  }
  return NO;
   }
  }

  - (void)textViewDidChange:(UITextView *)textView{
    self.placeholderLabel.hidden = self.hasText;
     UITextRange *selectedRange = [textView markedTextRange];
    //获取高亮部分
    UITextPosition *pos = [textView positionFromPosition:selectedRange.start offset:0];

   //如果在变化中是高亮部分在变，就不要计算字符了
   if (selectedRange && pos) {
  return;
   }

   NSString  *nsTextContent = textView.text;
   NSInteger existTextNum = nsTextContent.length;

   if (existTextNum > self.maxNum)
   {
  //截取到最大位置的字符(由于超出截部分在should时被处理了所在这里这了提高效率不再判断)
  NSString *s = [nsTextContent substringToIndex:self.maxNum];
  
  [textView setText:s];
  }
  if (existTextNum > 100) {
   existTextNum = 100;
    }
   //不让显示负数
 self.countLabel.text = [NSString 
 stringWithFormat:@"%ld/%ld",MAX(0, existTextNum),
 (long)self.maxNum
                      ];

 }
 #pragma mark - setter

- (void)setMaxNum:(NSInteger)maxNum{
   _maxNum = maxNum;
    self.countLabel.text = [NSString stringWithFormat:@"0/%ld",
   (long)_maxNum];
  }

- (void)setMyPlaceholder:(NSString *)myPlaceholder{
      _myPlaceholder = myPlaceholder;
      self.placeholderLabel.text = _myPlaceholder;
      ///重新计算占位label frame
      [self setNeedsLayout];
    }

- (void)setMyPlaceholderColor:(UIColor *)myPlaceholderColor{
          _myPlaceholderColor = myPlaceholderColor;
          self.countLabel.textColor = myPlaceholderColor;
          self.placeholderLabel.textColor = _myPlaceholderColor;
      }

  ///从写TextView setFont方法 使占位labe、TextView、文字统计
    Label Font一致
- (void)setFont:(UIFont *)font{
          [super setFont:font];
          self.placeholderLabel.font = font;
          self.countLabel.font = font;
          ///重新计算占位label frame
          [self setNeedsLayout];
     }
    @end

*** Demo ***

   - (void)prepareForUI{
            ///添加到父控件
            WKTextView *textView = [[WKTextView alloc]initWithFrame:CGRectMake(50, 50, self.view.width - 100, 200)];
            ///设置文本输入框的占位字符
            textView.myPlaceholder = @"我是占位字符串...";
            textView.font = [UIFont systemFontOfSize:14];
            textView.maxNum = 100;
            [self.view addSubview:textView];
        }

相关属性都暴露了出来，可以自行设置，效果如下：

WKTextView.gif

史上最好用的UITextview子类

一.前言

二 .WKTextView源码

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