Currently, I need to implement the function of sending red envelopes in the project. I wrote a password input box control, mainly using the UIKeyInput protocol and CoreGraphics framework. The effect is similar to WeChat payment. If it feels good, I will share my ideas and production process. Write it down and share it with everyone.

Let your custom View have the input function (UIKeyInput protocol)

The UIKeyInput protocol can provide the responder with a simple keyboard input function. Just make the responder that requires a keyboard the first responder. There are three methods that must be implemented in the UIKeyInput protocol, which are the following methods:

#pragma mark - UIKeyInput
/**
 * 用于顯示的文本對象是否有任何文本
 */
- (BOOL)hasText {
  return self.textStore.length > 0;
}
 
/**
 * 插入文本
 */
- (void)insertText:(NSString *)text {
  if (self.textStore.length < self.passWordNum) {
    //判斷是否是數(shù)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];
    }
  }
}
 
/**
 * 刪除文本
 */
- (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];
}
 
/**
 * 是否能成為第一響應者
 */
- (BOOL)canBecomeFirstResponder {
  return YES;
}
 
/**
 * 點擊成為第一相應者
 */
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
  if (![self isFirstResponder]) {
    [self becomeFirstResponder];
  }
}

Draw the password input box through CoreGraphics

The idea of ????implementation is to draw the outer frame and outline of the password input box through the CoreGraphics framework. The small black dot inside is then used to determine the number of input digits based on the string obtained from the keyboard. The specific implementation is as follows:

/**
 * 設置正方形的邊長
 */
- (void)setSquareWidth:(CGFloat)squareWidth {
  _squareWidth = squareWidth;
  [self setNeedsDisplay];
}
 
/**
 * 設置鍵盤的類型
 */
- (UIKeyboardType)keyboardType {
  return UIKeyboardTypeNumberPad;
}
 
/**
 * 設置密碼的位數(shù)
 */
- (void)setPassWordNum:(NSUInteger)passWordNum {
  _passWordNum = passWordNum;
  [self setNeedsDisplay];
}
 
/**
 * 繪制
 */
- (void)drawRect:(CGRect)rect {
  CGFloat height = rect.size.height;
  CGFloat width = rect.size.width;
  CGFloat x = (width - self.squareWidth*self.passWordNum)/2.0;
  CGFloat y = (height - self.squareWidth)/2.0;
  CGContextRef context = UIGraphicsGetCurrentContext();
  //畫外框
  CGContextAddRect(context, CGRectMake( x, y, self.squareWidth*self.passWordNum, self.squareWidth));
  CGContextSetLineWidth(context, 1);
  CGContextSetStrokeColorWithColor(context, self.rectColor.CGColor);
  CGContextSetFillColorWithColor(context, [UIColor whiteColor].CGColor);
  //畫豎條
  for (int i = 1; i <= self.passWordNum; i++) {
    CGContextMoveToPoint(context, x+i*self.squareWidth, y);
    CGContextAddLineToPoint(context, x+i*self.squareWidth, y+self.squareWidth);
     CGContextClosePath(context);
  }
  CGContextDrawPath(context, kCGPathFillStroke);
  CGContextSetFillColorWithColor(context, self.pointColor.CGColor);
  //畫黑點
  for (int i = 1; i <= self.textStore.length; i++) {
    CGContextAddArc(context, x+i*self.squareWidth - self.squareWidth/2.0, y+self.squareWidth/2, self.pointRadius, 0, M_PI*2, YES);
    CGContextDrawPath(context, kCGPathFill);
  }
}

The above is the entire content of this article. I hope it will be helpful to everyone's learning. I hope everyone will support the PHP Chinese website.

For more iOS implementation of password input boxes similar to WeChat and Alipay (UIKeyInput protocol) related articles, please pay attention to the PHP Chinese website!