记一下模仿支付宝输入密码

头部加入<UITextFieldDelegate>

并声明全局变量

@property(nonatomic,strong)UITextField *textField;
@property(nonatomic,strong)NSMutableArray *tfArray;

-(void)initUI{
    _tfArray = [[NSMutableArray alloc] initWithArray:@[[UITextField new],[UITextField new],[UITextField new],[UITextField new],[UITextField new],[UITextField new]]];
    [_tfArray enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        UITextField *textField = (UITextField *)obj;
        textField.backgroundColor = [UIColor clearColor];
        textField.tintColor = [UIColor clearColor];
        textField.enabled = NO;
        textField.font = Font_20;
      
        textField.textAlignment = NSTextAlignmentCenter;
        textField.tag = idx;
        [self.view addSubview:textField];
    }];
    [_tfArray mas_distributeViewsAlongAxis:MASAxisTypeHorizontal withFixedSpacing:15 leadSpacing:55 tailSpacing:55];
    [_tfArray mas_makeConstraints:^(MASConstraintMaker *make) {
        make.top.mas_equalTo(noticeLab.mas_bottom).mas_offset(30);
        make.height.mas_equalTo(60);
    }];

    _textField = [UITextField new];
    _textField.delegate = self;
    [_textField addTarget:self action:@selector(textChange:) forControlEvents:UIControlEventEditingChanged];
    _textField.backgroundColor = [UIColor clearColor];
    _textField.textColor = [UIColor clearColor];
    _textField.tintColor = [UIColor clearColor];
    _textField.keyboardType = UIKeyboardTypeNumberPad;
    [self.view addSubview:_textField];
    [_textField mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.equalTo(self.view).offset(55);
        make.right.equalTo(self.view).offset(-55);
        make.top.equalTo(_tfArray[0]);
        make.bottom.equalTo(_tfArray[0]);
    }];

}

-(void)textChange:(UITextField *)textField{
    if (textField.text.length > _tfArray.count) {
        _textField.text = [_textField.text substringWithRange:NSMakeRange(0,_tfArray.count)];
    }
    else
    {
        NSString *subStr = [textField.text substringWithRange:NSMakeRange(textField.text.length-1, 1)];
        if(textField.text.length >0)
        {
            UITextField *boxTextField = [_tfArray objectAtIndex:(textField.text.length-1)];
            boxTextField.text = subStr;
            if (boxTextField == _tfArray.lastObject) {
                [self checkSms:_textField.text];
            }
        }
    }
}

- (void)textFieldDidDeleteBackward:(UITextField *)textField {
    NSLog(@"%@",textField.text);
    UITextField *boxTextField = [_tfArray objectAtIndex:(textField.text.length)];
    boxTextField.text = @"";
}