export interface ILoaderReturnValue {
    [key: string]: {
        success: boolean;
        error?: Error;
    };
}
export declare abstract class Loader<T> {
    isLoading: boolean;
    abstract isAssetLoaded(_key: string): boolean;
    abstract add(_key: string, _asset: string): void;
    abstract has(_key: string): boolean;
    abstract get<T>(_key: string): T;
    /**
     * Load any enqueued assets, resolves when done
     * @param _onProgress Function callback with progress parameter (expressed as 0 to 100 because Facebook)
     */
    abstract load(_onProgress?: (progress: number) => void): Promise<ILoaderReturnValue>;
    abstract unload(_key: string): void;
    abstract cache<T>(_key: string, _asset: T): void;
}