iphone - 消息发送到应该存在的对象上的已释放实例

Question

[CFString isEqualToString:]:发送到已释放实例的消息

这是我收到的错误。我有一个 View Controller ，其属性是 NSMutableArray，它包含一些 Player 对象。

然后我有一个切换到另一个 View 的方法，我可以在其中添加和删除玩家。当我加载下一个 View 时，我将指针传递给第一个 View 和第二个 View 。然后，我使用 [previousView.playerList addObject:p]; 更新了数组，其中 p 是新创建的玩家对象。

但是，当我尝试在第二个 View 的 TableView 中显示玩家列表时，出现错误。当我尝试访问 [previousView.playerlist objectAtIndex:[indexPath row]]; 时，出现上述错误。

代码如下:

这是在第一个 View 中，它加载第二个 View 并将其自身传递给第二个 View 的属性。

- (IBAction) addPlayerButton:(id)sender {
    [self retain];
    PlayerListViewController *playerListViewController = [[PlayerListViewController alloc] init];
    playerListViewController.previousView = self;
    [UIView transitionFromView:self.view toView:playerListViewController.view duration:0.5 options:UIViewAnimationOptionTransitionFlipFromLeft completion:nil];
}

这是我初始化播放器并将其添加到数组中的地方。

- (IBAction)addPlayer:(id)sender {
    Player *p = [[[Player alloc] initWithPlayerName:playerNameField.text withOrder:[previousView.playerList count] withDelegate:previousView] retain];
    [previousView.playerList addObject:p];
    [playerNameField resignFirstResponder];
    [playerTableView reloadData];
}

这是我收到错误的地方

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *cellIdentifier = @"MyCell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier] autorelease];
    }
    Player* p = [previousView.playerList objectAtIndex:[indexPath row]];
    [cell.textLabel setText:[p playerName]];
    cell.accessoryType = UITableViewCellAccessoryCheckmark;

    return cell;
}

我在设置单元格文本的行上收到错误。 [cell.textLabel setText:[p 玩家名称]];

有人知道我哪里搞砸了吗？如果需要，我会发布更多代码。

我将 Player.m 修剪为仅包含综合和初始化，因为其余的代码很多，这与此错误无关，因为它没有被调用。

玩家.h

@protocol playerProtocol <NSObject>

@optional
- (void) playerDied:(id)playerObject;
- (void) playerWasAdded:(id)playerObject;
- (void) playerLifeDidChange:(id)playerObject;
@end

@interface Player : NSObject {
    id <playerProtocol> delegate;
}
@property (nonatomic,retain) NSString *playerName;
@property (nonatomic, readwrite) int playerLife;
@property (nonatomic, readwrite) int playerPoison;
@property (nonatomic, readwrite) int order;
@property (nonatomic, readwrite) Boolean invincible;
@property (nonatomic, assign) id <playerProtocol>delegate;
@property (nonatomic, retain) UIView *viewPane;
@property (nonatomic) Boolean shown;
@property (nonatomic, readwrite) int minusButton;
@property (nonatomic, readwrite) int plusButton;
@property (nonatomic, retain) UIImageView *readout;
@property (nonatomic, retain) NSArray *playerLifeNumerals;


- (id) initWithPlayerName:(NSString *)playersName withOrder:(int)Order withDelegate:(id)d;
- (void) setPlayerLife:(int)pplayerLife;
- (void) setPlayerPoison:(int)pplayerPoison;
- (NSArray *) getLifeNumeralsFromPlayer:(Player *)playerObject;

@end

玩家.m

@implementation Player

@synthesize playerLife, playerName, playerPoison, order, delegate, invincible, viewPane, readout, shown, minusButton, plusButton, playerLifeNumerals;

#pragma mark - Custom Initalizer

- (id) initWithPlayerName:(NSString *)playersName withOrder:(int)Order withDelegate:(id)d {

    [super init];
    delegate = d;
    playerLife = 20;
    playerPoison = 0;
    order = Order;
    playerName = playersName;
    invincible = NO;
    [delegate playerWasAdded:self];
    viewPane = nil;
    readout = nil;
    shown = NO;
    return self;
}

这里还有数组声明@property (nonatomic, keep) NSMutableArray *playerList;

Answer 1

在:

- (id) initWithPlayerName:(NSString *)playersName withOrder:(int)Order withDelegate:(id)d {

    [super init];
    delegate = d;
    playerLife = 20;
    playerPoison = 0;
    order = Order;
    playerName = playersName;
    invincible = NO;
    [delegate playerWasAdded:self];
    viewPane = nil;
    readout = nil;
    shown = NO;
    return self;
}

您没有保留playerName。请注意，虽然您已将 playerName 属性声明为 retain(并且应该改为 copy)，但您并未使用属性 setter 在-initWith…中。相反，您直接访问支持实例变量。由于您直接将 playersName 分配给实例变量，因此您需要手动发送 -retain (或者更好的是，-copy) .

检查您在其他声明的属性中是否需要此属性。另外，您应该遵循以下习惯用法:

self = [super init];
if (self) { … }
return self;

在你的初始化程序中。

编辑:您需要仔细检查有关内存管理实践的代码，因为您在多个地方发生泄漏。例如，在:

- (IBAction) addPlayerButton:(id)sender {
    [self retain];
    PlayerListViewController *playerListViewController = [[PlayerListViewController alloc] init];
    playerListViewController.previousView = self;
    [UIView transitionFromView:self.view toView:playerListViewController.view duration:0.5 options:UIViewAnimationOptionTransitionFlipFromLeft completion:nil];
}

[ self 保留]的目的是什么，是否有平衡释放？

另一个例子:在:

Player *p = [[[Player alloc] initWithPlayerName:playerNameField.text withOrder:[previousView.playerList count] withDelegate:previousView] retain];
[previousView.playerList addObject:p];

您从 +alloc 获得 +1 所有权，从 -retain 获得另一个 +1，并且该数组还拥有 p，因此另一个+1。您应该将 -retain 替换为 -autorelease 以平衡您获得该对象所有权的次数。