Wait for data in controller before link function is run in AngularJS directive

Question

How can I ensure that data from a controller has been loaded in a directive before the link function is run?

Using psuedo-code, I could have:

Answer 1

app.directive('MyDirective', function() {
    return {
        controller: function() {
            this.$postLink = function() {
                // here will run after the link function and also after the binding came in
            };
        },
        controllerAs: 'vm'
    };
});

check out the angular 1.5 Components have a well-defined lifecycle and it works on directives to