- (void)drawBackground:(CGSize)size{
     
    self.gridWidth = (size.width - 2 * kBoardSpace) / self.gridCount;
     
    //1.开启图像上下文
    UIGraphicsBeginImageContext(size);
    //2.获取上下文
    CGContextRef ctx = UIGraphicsGetCurrentContext();
     
    CGContextSetLineWidth(ctx, 0.8f);
    //3.1 画16条竖线
    for (int i = 0; i <= self.gridCount; i ++) {
      CGContextMoveToPoint(ctx, kBoardSpace + i * self.gridWidth , kBoardSpace);
      CGContextAddLineToPoint(ctx, kBoardSpace + i * self.gridWidth , kBoardSpace + self.gridCount * self.gridWidth);
    }
    //3.1 画16条横线
    for (int i = 0; i <= self.gridCount; i ++) {
      CGContextMoveToPoint(ctx, kBoardSpace, kBoardSpace + i * self.gridWidth );
      CGContextAddLineToPoint(ctx, kBoardSpace + self.gridCount * self.gridWidth , kBoardSpace + i * self.gridWidth);
    }
    CGContextStrokePath(ctx);
     
    //4.获取生成的图片
    UIImage *image=UIGraphicsGetImageFromCurrentImageContext();
    //5.显示生成的图片到imageview
    UIImageView * imageView = [[UIImageView alloc]initWithImage:image];
    [self addSubview:imageView];
    UIGraphicsEndImageContext();
}

//点击棋盘,下棋
  - (void)tapBoard:(UITapGestureRecognizer *)tap{
   
    CGPoint point = [tap locationInView:tap.view];
    //计算下子的列号行号
    NSInteger col = (point.x - kBoardSpace + 0.5 * self.gridWidth) / self.gridWidth;
    NSInteger row = (point.y - kBoardSpace + 0.5 * self.gridWidth) / self.gridWidth;
    NSString * key = [NSString stringWithFormat:@"%ld-%ld",col,row];
    if (![self.chessmanDict.allKeys containsObject:key]) {
      UIView * chessman = [self chessman];
      chessman.center = CGPointMake(kBoardSpace + col * self.gridWidth, kBoardSpace + row * self.gridWidth);
      [self addSubview:chessman];
      [self.chessmanDict setValue:chessman forKey:key];
      self.lastKey = key;
      //检查游戏结果
      [self checkResult:col andRow:row andColor:self.isBlack];
      self.isBlack = !self.isBlack;
    }
  }

//判断是否大于等于五个同色相连
  - (BOOL)checkResult:(NSInteger)col andRow:(NSInteger)row andColor:(BOOL)isBlack andDirection:(GmkDirection)direction{
   
    if (self.sameChessmanArray.count >= 5) {
      return YES;
    }
    UIColor * currentChessmanColor = [self.chessmanDict[[NSString stringWithFormat:@"%ld-%ld",col,row]] backgroundColor];
    [self.sameChessmanArray addObject:self.chessmanDict[self.lastKey]];
    switch (direction) {
      //水平方向检查结果
      case GmkHorizontal:{
        //向前遍历
        for (NSInteger i = col - 1; i > 0; i --) {
          NSString * key = [NSString stringWithFormat:@"%ld-%ld",i,row];
          if (![self.chessmanDict.allKeys containsObject:key] || [self.chessmanDict[key] backgroundColor] != currentChessmanColor) break;
          [self.sameChessmanArray addObject:self.chessmanDict[key]];
        }
        //向后遍历
        for (NSInteger i = col + 1; i < kGridCount; i ++) {
          NSString * key = [NSString stringWithFormat:@"%ld-%ld",i,row];
          if (![self.chessmanDict.allKeys containsObject:key] || [self.chessmanDict[key] backgroundColor] != currentChessmanColor) break;
          [self.sameChessmanArray addObject:self.chessmanDict[key]];
        }
        if (self.sameChessmanArray.count >= 5) {
          [self alertResult];
          return YES;
        }
        [self.sameChessmanArray removeAllObjects];
         
      }
        break;
      case GmkVertical:{
        //向前遍历
        for (NSInteger i = row - 1; i > 0; i --) {
          NSString * key = [NSString stringWithFormat:@"%ld-%ld",col,i];
          if (![self.chessmanDict.allKeys containsObject:key] || [self.chessmanDict[key] backgroundColor] != currentChessmanColor) break;
          [self.sameChessmanArray addObject:self.chessmanDict[key]];
        }
        //向后遍历
        for (NSInteger i = row + 1; i < kGridCount; i ++) {
          NSString * key = [NSString stringWithFormat:@"%ld-%ld",col,i];
          if (![self.chessmanDict.allKeys containsObject:key] || [self.chessmanDict[key] backgroundColor] != currentChessmanColor) break;
          [self.sameChessmanArray addObject:self.chessmanDict[key]];
        }
        if (self.sameChessmanArray.count >= 5) {
          [self alertResult];
          return YES;
        }
        [self.sameChessmanArray removeAllObjects];
         
      }
        break;
      case GmkObliqueDown:{
         
        //向前遍历
        NSInteger j = col - 1;
        for (NSInteger i = row - 1; i >= 0; i--,j--) {
          NSString * key = [NSString stringWithFormat:@"%ld-%ld",j,i];
          if (![self.chessmanDict.allKeys containsObject:key] || [self.chessmanDict[key] backgroundColor] != currentChessmanColor || j < 0) break;
          [self.sameChessmanArray addObject:self.chessmanDict[key]];
        }
        //向后遍历
        j = col + 1;
        for (NSInteger i = row + 1 ; i < kGridCount; i++,j++) {
          NSString * key = [NSString stringWithFormat:@"%ld-%ld",j,i];
          if (![self.chessmanDict.allKeys containsObject:key] || [self.chessmanDict[key] backgroundColor] != currentChessmanColor || j > kGridCount) break;
          [self.sameChessmanArray addObject:self.chessmanDict[key]];
        }
        if (self.sameChessmanArray.count >= 5) {
          [self alertResult];
          return YES;
        }
        [self.sameChessmanArray removeAllObjects];
         
       
      }
        break;
      case GmkObliqueUp:{
        //向前遍历
        NSInteger j = col + 1;
        for (NSInteger i = row - 1; i >= 0; i--,j++) {
          NSString * key = [NSString stringWithFormat:@"%ld-%ld",j,i];
          if (![self.chessmanDict.allKeys containsObject:key] || [self.chessmanDict[key] backgroundColor] != currentChessmanColor || j > kGridCount) break;
          [self.sameChessmanArray addObject:self.chessmanDict[key]];
        }
        //向后遍历
        j = col - 1;
        for (NSInteger i = row + 1 ; i < kGridCount; i++,j--) {
          NSString * key = [NSString stringWithFormat:@"%ld-%ld",j,i];
          if (![self.chessmanDict.allKeys containsObject:key] || [self.chessmanDict[key] backgroundColor] != currentChessmanColor || j < 0) break;
          [self.sameChessmanArray addObject:self.chessmanDict[key]];
        }
        if (self.sameChessmanArray.count >= 5) {
          [self alertResult];
          return YES;
        }
        [self.sameChessmanArray removeAllObjects];
         
      }
        break;
    }
    return NO;
  }

- (void)newGame{
     
    self.isOver = NO;
    self.lastKey = nil;
    [self.sameChessmanArray removeAllObjects];
    self.userInteractionEnabled = YES;
    [self.chessmanDict removeAllObjects];
    for (UIView * view in self.subviews) {
      if ([view isKindOfClass:[UIImageView class]]) {
        continue;
      }
      [view removeFromSuperview];
    }
    self.isBlack = NO;
  }

//撤回至上一步棋
  - (void)backOneStep:(UIButton *)sender{
   
    if(self.isOver) return;
     
    if (self.lastKey == nil) {
      sender.enabled = NO;
      CGFloat width = SCREEN_WIDTH * 0.4 * SCREEN_WIDTH_RATIO;
      UIView * tip = [[UIView alloc]initWithFrame:CGRectMake(0, 0, width, 0.6 * width)];
      tip.backgroundColor = [UIColor colorWithWhite:1 alpha:0.8];
      tip.layer.cornerRadius = 8.0f;
      [self addSubview:tip];
      tip.center = CGPointMake(self.width * 0.5, self.height * 0.5);
      UILabel * label = [[UILabel alloc]init];
      label.text = self.chessmanDict.count > 0 ? @"只能悔一步棋!!!" : @"请先落子!!!";
      label.font = [UIFont systemFontOfSize:15];
      [label sizeToFit];
      label.center = CGPointMake(tip.width * 0.5, tip.height * 0.5);
      [tip addSubview:label];
       
      self.userInteractionEnabled = NO;
      dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        self.userInteractionEnabled = YES;
        sender.enabled = YES;
        [tip removeFromSuperview];
         
      });
      return;
    }
    [self.chessmanDict removeObjectForKey:self.lastKey];
    [self.subviews.lastObject removeFromSuperview];
    self.isBlack = !self.isBlack;
    self.lastKey = nil;
  }

//改变键盘级别
  - (void)changeBoardLevel{
     
    for (UIView * view in self.subviews) {
      [view removeFromSuperview];
    }
    [self newGame];
    self.isHighLevel = !self.isHighLevel;
    [self drawBackground:self.bounds.size];
  }