AngularJS で ng-class を使用する方法についての簡単な説明

function ctrl($scope) { 
  $scope.className = "selected";
}

<div class="{{className}}"></div>

function ctrl($scope) { 
  $scope.isSelected = true;
}

<div ng-class="{true:&#39;selected&#39;,false:&#39;unselected&#39;}[isSelected]"></div>

function ctrl($scope) { 
  $scope.isA = true;
  $scope.isB = false;
  $scope.isC = false;
}

<div ng-class="{&#39;A&#39;:isA,&#39;B&#39;:isB,&#39;C&#39;:isC}"></div>

<ion-list>
  <ion-item ng-repeat="project in projects" ng-click="selectProject(project, $index)" ng-class="{active: activeProject == project}">
    {{project.title}}
  </ion-item>
</ion-list>