• 现在app中时常用到六位密码，而这种密码输入框则需要我们自己来编写。

实现

六位密码框并不是一个被分成六格的textfield，而是由一个隐藏的textfield与六个label实现。其原理主要是通过监控textfield里面值的变化，从而动态改变label的值，而形成输入了值的假象。

1、UITextField定义

- (UITextField *)pswTF{
    if (!_pswTF) {
        _pswTF = [[UITextField alloc] init];
        
        _pswTF.delegate = self;
        
        _pswTF.keyboardType = UIKeyboardTypeNumberPad;
        
        //添加对输入值的监视
        [_pswTF addTarget:self action:@selector(valueChange:) forControlEvents:UIControlEventEditingChanged];
    }
    
    return _pswTF;
}

2、添加点击事件，使点击输入框开启键盘

  UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(click)];
        
  [self addGestureRecognizer:tap];

3、添加label与分割线的绘制

#pragma mark - 设置UI
- (void)initUI{
    self.backgroundColor = [UIColor whiteColor];
    
    [self addSubview:self.pswTF];
    
    //添加6个label
    for (int i = 0; i < 6; i++) {
        UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(i*self.frame.size.width/6.0, 0, self.frame.size.width/6.0, self.frame.size.height)];
        
        label.textAlignment = NSTextAlignmentCenter;
        
        label.tag = 100 + i;
        
        [self addSubview:label];
    }
    
    //设置边框圆角与颜色
    self.layer.masksToBounds = YES;
    self.layer.cornerRadius = 10.0;
    self.layer.borderColor = [UIColor blackColor].CGColor;
    self.layer.borderWidth = 2;
}

//划线
- (void)drawRect:(CGRect)rect{
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    CGContextSetLineWidth(context, 2);
    
    //设置分割线颜色
    CGContextSetRGBStrokeColor(context, 0, 0, 0, 1);
    
    CGContextBeginPath(context);
    
    //5条分割线绘制
    for (int i = 0; i < 5;  i++){
        CGContextMoveToPoint(context, self.frame.size.width/6.0 * (i + 1), 0);
        CGContextAddLineToPoint(context,self.frame.size.width/6.0 * (i + 1) , self.frame.size.height);
    }
    
    CGContextStrokePath(context);
    
}

4、监控textfield值，改变label

- (void)valueChange:(UITextField *)textField{
    NSString *text = textField.text;

    if (text.length <= 6){    //当输入小于6的时候
        for (int i = 0; i < 6; i++) {
            //通过tag获取label
            UILabel *label = (UILabel *)[self viewWithTag:100 + i];
            
            //更改label值
            if (i < text.length) {
                label.text = @"*";
            }
            else{
                label.text = @"";
            }
        }
    }
    else{ //输入值长度大于6时，截取字符串
        textField.text = [text substringWithRange:NSMakeRange(0, 6)];
    }
    
    NSLog(@"%@",textField.text);
}

5、返回密码

- (NSString *)getPsw{
    return self.pswTF.text;
}

• 这样六位密码输入框就实现了，具体可以查看我的DEMO