text: //
  //  BLDataSource.h
  //  https://github.com/batkov/BLDataSource
  //
  // Copyright (c) 2016 Hariton Batkov
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included in all
  // copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  // SOFTWARE.
  
  #import <Foundation/Foundation.h>
  #import "BLDataKeys.h"
  
  @protocol BLDataSourceDelegate;
  
  @interface BLDataSource : NSObject
  
  @property (weak, nonatomic, nullable) id <BLDataSourceDelegate> delegate;
  @property (copy, nonatomic, nullable) BLDataSourceStateBlock stateChangedBlock;
  
  @property (assign, nonatomic, readonly) BLDataSourceState state;
  @property (strong, nonatomic, readonly, nullable) NSError *lastError;
  
  - (BOOL)hasContent;
  - (void)startContentLoading;
  - (void)startContentRefreshing;
  - (BOOL)canRefresh;
  
  @end
  
  @protocol BLDataSourceDelegate <NSObject>
  - (void)dataSource:(BLDataSource * _Nonnull)dataSource stateChanged:(BLDataSourceState)state;
  @end
  