在我的游戏模型中需要内存管理问题的帮助

Question

我是一名尝试为iphone制作游戏应用程序的初学者级别程序员，并且迄今为止我遇到了我的程序的内存管理（exc_bad_access）可能存在的问题。我搜索并阅读了许多关于内存管理的文章（包括苹果的文档），但我仍然无法弄清楚我的代码究竟出了什么问题。所以如果有人能帮助我清理我为自己制造的混乱，我会非常感激。

//in the .h file 
@property(nonatomic,retain) NSMutableArray *fencePoleArray; 
@property(nonatomic,retain) NSMutableArray *fencePoleImageArray; 
@property(nonatomic,retain) NSMutableArray *fenceImageArray; 

//in the .m file 
- (void)viewDidLoad { 
    [super viewDidLoad]; 
    self.gameState = gameStatePaused; 

    fencePoleArray = [[NSMutableArray alloc] init]; 
    fencePoleImageArray = [[NSMutableArray alloc] init]; 
    fenceImageArray = [[NSMutableArray alloc] init]; 

    mainField = CGRectMake(10, 35, 310, 340); 

    .......... 

    [NSTimer scheduledTimerWithTimeInterval:0.05 target:self selector:@selector(gameLoop) userInfo:nil repeats:YES]; 
} 

所以基本上，玩家触摸屏幕来设置围栏/极

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { 
    if(.......) { 

    ....... 

    } 
    else { 
     UITouch *touch = [[event allTouches] anyObject]; 
     currentTapLoc = [touch locationInView:touch.view]; 

     NSLog(@"%i, %i", (int)currentTapLoc.x, (int)currentTapLoc.y); 

     if(CGRectContainsPoint(mainField, currentTapLoc)) { 
      if([self checkFence]) { 
       onFencePole++; 
       //this 3 set functions adds their respective objects into the 3 NSMutableArrays using addObject: 
       [self setFencePole]; 
       [self setFenceImage]; 
       [self setFencePoleImage]; 

       ....... 

       } 
      } 
      else { 
       ....... 
      } 
     } 
    } 
} 

的setFence功能（setFenceImage和setFencePoleImage与此类似）

-(void)setFencePole { 
    Fence *fencePole; 
    if (!elecFence) { 
     fencePole = [[Fence alloc] initFence:onFencePole fenceType:1 fencePos:currentTapLoc]; 
    } 
    else { 
     fencePole = [[Fence alloc] initFence:onFencePole fenceType:2 fencePos:currentTapLoc]; 
    } 
    [fencePoleArray addObject:fencePole]; 
    [fencePole release]; 

，每当我按下游戏中的按钮，调用endOpenState来清除屏幕上的所有额外图像（栅栏/极点），并删除3个NSMutableArray中的所有现有对象。点是删除NSMutableArrays中的所有对象，但保留数组本身，以便稍后可以重用。

-(void)endOpenState { 

    ........ 

    int xMax = [fencePoleArray count]; 
    int yMax = [fenceImageArray count]; 

    for (int x = 0; x < xMax; x++) { 
     [[fencePoleImageArray objectAtIndex:x] removeFromSuperview]; 
    } 

    for (int y = 0; y < yMax; y++) { 
     [[fenceImageArray objectAtIndex:y] removeFromSuperview]; 
    } 

    [fencePoleArray removeAllObjects]; 
    [fencePoleImageArray removeAllObjects]; 
    [fenceImageArray removeAllObjects]; 

    ........ 
} 

崩溃发生在checkFence函数的这里。

-(BOOL)checkFence { 
    if (onFencePole == 0) { 
     return YES; 
    } 
    else if (onFencePole >= 1 && onFencePole < currentMaxFencePole - 1) { 
     CGPoint tempPoint1 = currentTapLoc; 
     CGPoint tempPoint2 = [[fencePoleArray objectAtIndex:onFencePole-1] returnPos]; // the crash happens at this line 
     if ([self checkDistance:tempPoint1 point2:tempPoint2]) { 
      return YES; 
     } 
     else { 
      return NO; 
     } 
    } 
    else if (onFencePole == currentMaxFencePole - 1) { 

    ...... 

    } 
    else { 
     return NO; 
    } 
} 

所以这里的问题是，一切工作正常，直到checkFence调用endOpenState后第二次调用。因此，它像tap_screen - > tap_screen - > press_button_to_call_endOpenState - >自来水屏幕 - > tap_screen - >崩溃

的我在想什么是fencePoleArray弄乱，当我用[fencePoleArray removeAllObjects]，因为它不会崩溃的时候我评论一下。如果有人能向我解释出了什么问题，那真的很棒。并提前致谢。

Answer 1

首先，一对夫妇的建议：

if (!elecFence) { 
    fencePole = [[Fence alloc] initFence:onFencePole 
     fenceType:1 fencePos:currentTapLoc]; 
} 
else { 
    fencePole = [[Fence alloc] initFence:onFencePole 
     fenceType:2 fencePos:currentTapLoc]; 
} 

你正在做这个太辛苦了，这个怎么样：

const int fenceType = elecFence ? 2 : 1; 
Fence *fencePole = [[Fence alloc] initFence:onFencePole 
     fenceType:fenceType fencePos:currentTapLoc]; 

这：

int xMax = [fencePoleArray count]; 
int yMax = [fenceImageArray count]; 

for (int x = 0; x < xMax; x++) { 
    [[fencePoleImageArray objectAtIndex:x] removeFromSuperview]; 
} 

for (int y = 0; y < yMax; y++) { 
    [[fenceImageArray objectAtIndex:y] removeFromSuperview]; 
} 

可以缩短使用makeObjectsPerformSelector:

const SEL remove = @selector(removeFromSuperview); 
[fencePoleImageArray makeObjectsPerformSelector:remove]; 
[fenceImageArray makeObjectsPerformSelector:remove]; 

这会更短更安全，因为代码中的xMax从fencePoleArray开始计算并用于迭代fencePoleImageArray。 （可能是对的，可能是错的。）

现在拨打objectAtIndex:。如果数组仍然在内存中，并且您试图访问超出数组边界的对象，则会发生异常。因此，我猜想数组或其中的某些对象在您不知情的情况下被释放。您可以尝试NSLog阵列和给定索引上的对象，并尝试记录它们的retainCount。如果日志记录行崩溃，则已找到已释放的对象并可开始查找原因。

（还有一两件事：你应该在游戏逻辑拆分成一个独立的模型类，简化了代码，并使得它更容易推理。）

Answer 2

如果你想使用属性，你应该使用self.propertyName = ...而不是propertyName = ...。

希望这会有所帮助。