Creating a "Like" button with Angular.js - angularjs

Question

Im trying to create a like button with Angular.js.
(It is just a heart icon. default color is white = NOT liked. It is red when liked. Like/unlike is toggled by a click)
I get some data from my web service that has also an array of some ID's. These ID's are the ones that clicked the like button before.
Then i populate the DOM with the ng-repeat directive according to the data retrieved from the web service.
I attach the button a ng-class that sets the proper class and a ng-click directive that is supposed to somehow change the class too.
* I cant connect between the ng-class and the ng-click result.
some code:
<div ng-repeat="photo in photos track by photo._id">
<button ng-class="{carouselFooterButtonLikeActive : initLike(photo)}" ng-click="like(photo, this)">
<i class="icon ion-heart"></i>
</button>
</div>
Controller:
// Handle like button click
$scope.like = function(photo, photoScope){
HOW CAN I AFFECT THE NG-CLASS FROM HERE?
}
$scope.initLike = function(photo){
if(photo.likes.indexOf($localstorage.getObject('userInfo').id) > -1) {
$scope.liked = true;
return true;
}
$scope.liked = false;
return false;
}
Edit: added a possible data retrieved from the web service
{
photos: [
{
src: "src1.jpg",
likes:[111,222,333]
},
{
src: "src2.jpg",
likes:[]
}
]
}

Answer 1

You can use as a flag some additional property that will be initially undefined on each photo element - say photo.liked. When user clicks it, $scope.like function sets this property to true. Then ng-class evaluates photo.liked to true and adds carouselFooterButtonLikeActive class to button element.
The code is as follows:
In the template:
<button ng-class="{'carouselFooterButtonLikeActive' : photo.liked}" ng-click="like(photo, this)">
In the controller:
$scope.like = function(photo, photoScope){
photo.liked = true;
}
UPD
Say you have photos array:
[
{'src':'bla-bla.jpg', liked: true, id: 8347},
{'src':'foo-bar.jpg', id: 45},
{'src':'baz-baz.jpg', id: 47}
]
then only the first one will be shown with button.carouselFooterButtonLikeActive class, thanks to ng-class evaluation expression.
UPD2
If photo.likes is an array, you can use:
//template
ng-class="{'carouselFooterButtonLikeActive' : (photo.likes && photo.likes.length >0)}"
//controller
$scope.like = function(photo, photoScope){
photo.likes.push(someUserID);
}