修改光标颜色、placeholder 颜色，手机号输入格式化

• 修改光标颜色

  //修改textField光标颜色，
  [textField setTintColor:[UIColor redColor]];
  //设置UITextField的光标颜色
  // [[UITextField appearance] setTintColor:[UIColor redColor];
  

• 修改placeholder 颜色

通过设置UITextField的attributedPlaceholder属性，修改它的颜色 。因为经常用到，创建UITextField 的分类，将其封装。

/** 设置textfield的placeholder及其颜色  */
-(void)dh_setPlaceholder:(NSString *)placeholder andPlaceholderColor:(UIColor *)placeholderColor {
    NSDictionary *attributes = @{
                                 NSForegroundColorAttributeName:placeholderColor,
                                 NSFontAttributeName:self.font
                                 };
    NSAttributedString *attrString = [[NSAttributedString alloc] initWithString:placeholder attributes:attributes];
    self.attributedPlaceholder = attrString;
}

• 手机号输入格式化

  在用户输入电话号码时，自动将其格式化为123 4567 8910。

  -(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string;

  把textField中位置为range的字符串替换为string字符串；此函数在textField内容被修改时调用；使用这个方法来验证使用时用户输入的类型。

  @param textField textField

  @param range UITextField控件中光标选中的字符串，即被替换的字符串；range.length为0时，表示在位置range.location插入string。

  @param string 替换字符串；string.length为0时，表示删除。

  @return YES，表示修改生效；NO，表示不做修改，textField的内容不变。

  实现代码(ps:一下代码均实现在UITextField的分类中)：

  -(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
      //在输入或删除前的光标位置
      NSRange currentRange = [self cursorPosition];
      //输入或删除前的内容
      NSString *previousContent = textField.text;
      // 限制只能输入数字
      NSCharacterSet *characterSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789\b"];
      string = [string stringByReplacingOccurrencesOfString:@" " withString:@""];
      if ([string rangeOfCharacterFromSet:[characterSet invertedSet]].location != NSNotFound) {
          return NO;
      }
      //把textField中位置为range的字符串替换为string字符串
      NSString *handleText = [previousContent stringByReplacingCharactersInRange:range withString:string];
      //纯数字的字符串
      NSString *onlyDigitStr = [handleText stringByReplacingOccurrencesOfString:@" " withString:@""];
      NSMutableString *temMstr = [NSMutableString new];
      for (NSInteger i = 0; i < onlyDigitStr.length; i++) {
          if (i == 3 || i == 7) {
              [temMstr appendString:@" "];
          }
          unichar digitchar = [onlyDigitStr characterAtIndex:i];
          [temMstr appendString:[NSString stringWithCharacters:&digitchar length:1]];
      }
      if (temMstr.length >= 14) {
          return NO;
      }
      [textField setText:temMstr];
  /*
      //不做任何处理时，显示的内容
      NSString *text = [previousContent stringByReplacingCharactersInRange:range withString:string];
      text = [text stringByReplacingOccurrencesOfString:@" " withString:@""];
      NSMutableString *temString = [NSMutableString stringWithString:text];
      [temString insertString:@" " atIndex:0];
      text = temString;
      NSString *newString = @"";
      while (text.length > 0) {
          NSString *subString = [text substringToIndex:MIN(text.length, 4)];
          newString = [newString stringByAppendingString:subString];
          if (subString.length == 4) {
              newString = [newString stringByAppendingString:@" "];
          }
          text = [text substringFromIndex:MIN(text.length, 4)];
      }
      newString = [newString stringByTrimmingCharactersInSet:[characterSet invertedSet]];
      if (newString.length >= 14) {
          return NO;
      }
      [textField setText:newString];
  */
      if (string.length == 0) {
          //删除
          currentRange.location --;
          if (currentRange.location == 4 || currentRange.location == 9) {
              currentRange.location --;
          }
      }
      else {
          currentRange.location += string.length;
          if (currentRange.location == 4 || currentRange.location == 9) {
              currentRange.location ++;
          }
      }
      [self setCursorPosition:currentRange];
      return NO;
  }
  /**  光标位置  */
  - (NSRange)cursorPosition {
      UITextPosition* beginning = self.beginningOfDocument;
      UITextRange* selectedRange = self.selectedTextRange;
      UITextPosition* selectionStart = selectedRange.start;
      UITextPosition* selectionEnd = selectedRange.end;
      const NSInteger location = [self offsetFromPosition:beginning toPosition:selectionStart];
      const NSInteger length = [self offsetFromPosition:selectionStart toPosition:selectionEnd];
      return NSMakeRange(location, length);
  }
  /**  设置光标位置  */
  - (void)setCursorPosition:(NSRange) range {
      UITextPosition* beginning = self.beginningOfDocument;
      UITextPosition* startPosition = [self positionFromPosition:beginning offset:range.location];
      UITextPosition* endPosition = [self positionFromPosition:beginning offset:range.location + range.length];
      UITextRange* cursorPosition = [self textRangeFromPosition:startPosition toPosition:endPosition];
      [self setSelectedTextRange:cursorPosition];
  }