iOS는 WeChat 및 Alipay(UIKeyInput 프로토콜)와 유사한 비밀번호 입력 상자를 구현합니다.

#pragma mark - UIKeyInput
/**
 * 用于显示的文本对象是否有任何文本
 */
- (BOOL)hasText {
  return self.textStore.length > 0;
}
 
/**
 * 插入文本
 */
- (void)insertText:(NSString *)text {
  if (self.textStore.length < self.passWordNum) {
    //判断是否是数字
    NSCharacterSet *cs = [[NSCharacterSet characterSetWithCharactersInString:MONEYNUMBERS] invertedSet];
    NSString*filtered = [[text componentsSeparatedByCharactersInSet:cs] componentsJoinedByString:@""];
    BOOL basicTest = [text isEqualToString:filtered];
    if(basicTest) {
     if ([self.delegate respondsToSelector:@selector(passWordDidChange:)]) {
        [self.delegate passWordDidChange:self];
      }
      if (self.textStore.length == self.passWordNum) {
        if ([self.delegate respondsToSelector:@selector(passWordCompleteInput:)]) {
          [self.delegate passWordCompleteInput:self];
        }
      }
      [self.textStore appendString:text];
      [self setNeedsDisplay];
    }
  }
}
 
/**
 * 删除文本
 */
- (void)deleteBackward {
  if (self.textStore.length > 0) {
    [self.textStore deleteCharactersInRange:NSMakeRange(self.textStore.length - 1, 1)];
   if ([self.delegate respondsToSelector:@selector(passWordDidChange:)]) {
      [self.delegate passWordDidChange:self];
    }
  }
  [self setNeedsDisplay];
}
 
/**
 * 是否能成为第一响应者
 */
- (BOOL)canBecomeFirstResponder {
  return YES;
}
 
/**
 * 点击成为第一相应者
 */
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
  if (![self isFirstResponder]) {
    [self becomeFirstResponder];
  }
}