A simple todo list smart contract in Solidity

Todos.sol

pragma solidity ^0.4.0;

contract TodosContract {
    address private  _owner ;
    
    struct Todo {
        string title;
        bool completed;
    }

    mapping (address => Todo[]) public todos;
    
    event TodoCreated(address owner, uint todoId, string title);
    event TodoToggled(address owner, uint todoId, bool completed);

    function Todos() public {
        _owner = msg.sender;
    }
    
    function addTodo(string _title) public {
        require(bytes(_title).length != 0);
        uint id = todos[msg.sender].push(Todo(_title, false)) - 1;
        TodoCreated(msg.sender, id, _title);
    }
    
    function toggleTodo(uint _todoId) external {
        require(_todoId < todos[msg.sender].length);

        Todo storage todo = todos[msg.sender][_todoId];
        todo.completed = !todo.completed; 
        TodoToggled(msg.sender, _todoId, todo.completed);
    }
    
    function getTodosCount() public constant returns (uint){
        return todos[msg.sender].length;
    }
    
    function getTodos() public constant returns (Todo[]){
        return todos[msg.sender];
    }
    
        
    function getTodo(uint _todoId) public constant returns (Todo) {
        require(_todoId < todos[msg.sender].length);
        return todos[msg.sender][_todoId];
    }
    
    function getTodoTitle(uint _todoId) public constant returns (string) {
        Todo memory todo =  getTodo(_todoId);
        return todo.title;
    }
    
    function getTodoCompleted(uint _todoId) public constant returns (bool) {
        Todo memory todo =  getTodo(_todoId);
        return todo.completed;
    }
    
    function deleteContract() external {
        require(msg.sender == _owner);
        selfdestruct(_owner);
    }

    function () public {}
}