feat(loading): add setContent function

src/components/loading/loading.ts

@@ -36,6 +36,14 @@ export class Loading extends ViewController {
     return this._nav && this._nav.config.get(key);
   }
 
+  /**
+   * @param {string} content  loading message content
+   */
+  setContent(content: string) {
+    this.data.content = content;
+  }
+
+
   /**
    * Present the loading instance.
    *

src/components/nav/view-controller.ts

@@ -79,9 +79,9 @@ export class ViewController {
   didUnload: EventEmitter<any>;
 
   /**
-   * @private
+   * @protected
    */
-  data: any;
+  protected data: any;
 
   /**
    * @private