PHP: If-else statement in switch loop produces parse error

I have this code in one of my functions:

$condition = 1;
$bool = false;
$strict = false;
    switch($condition):

            case "true":
            case "1":
                if($strict == false):
                    if($value == true)$bool = true; //only works when if opened with ":" and closed with endif; 
                else:
                    if($value === true)$bool = true; //same applies here 
                endif; 
            break;

            case "ntrue":
            case "-1":
                if($strict == false):
                    if($value != true)$bool = true; //same applies here 
                else:
                    if($value !== true)$bool = true; //same applies here 
                endif;      
            break;
    endswitch;

The above code will produce parse error "unexpected ':'" on every "else:" line. Can I use opened if statements in switch loop (although it doesn't work if I close it with "{}" either) and if I can, what is happening there what makes the parsing error?