text: //
  //  NSObject+KVOBlock.h
  //  OverrideKVO
  //
  //  Created by Honey on 2019/5/8.
  //  Copyright © 2019 Honey. All rights reserved.
  //
  
  #import <Foundation/Foundation.h>
  
  typedef void(^KVOBlock)(id _Nullable observered, NSString * _Nullable key, id _Nullable newValue, id _Nullable oldValue);
  
  NS_ASSUME_NONNULL_BEGIN
  
  @interface NSObject (KVOBlock)
  
  // 添加观察者
  - (void)addObserver:(NSObject *)observer forKey:(NSString *)key options:(NSKeyValueObservingOptions)options block:(KVOBlock)block;
  // 删除观察者
  - (void)removeObserver:(NSObject *)observer forKey:(NSString *)key;
  
  @end
  
  NS_ASSUME_NONNULL_END
  