处理UIButtons iOS

Question

我一直在观看2013年冬季的iOS讲座（Paul Hegerty），我似乎无法理解为什么第二行代码在Matchisimo程序中是必要的。如果我将其评论出来，程序会崩溃，但如果我将其保留，则可以正常工作。

[cardButton setTitle:card.contents forState:UIControlStateSelected];

[cardButton setTitle:card.contents forState:UIControlStateSelected|UIControlStateDisabled];

在这一行失败：

@autoreleasepool {
    return UIApplicationMain(argc, argv, nil, NSStringFromClass([CardGameAppDelegate class]));
}

如果第二行被注释掉，则会出错：

'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 47 beyond bounds [0 .. 46]'

卡内容：

@property (strong, nonatomic) NSString *contents;

更新用户界面：

- (void)updateUI
{
    for (UIButton *cardButton in self.cardButtons) {
        Card *card = [self.game cardAtIndex:[self.cardButtons indexOfObject:cardButton]];

        [cardButton setTitle:card.contents forState:UIControlStateSelected];

        [cardButton setTitle:card.contents forState:UIControlStateSelected|UIControlStateDisabled];

        cardButton.selected = card.isFaceUp;
        cardButton.enabled = !card.isUnPlayable;
    }
}

Answer 1

评论此行[cardButton setTitle:card.contents forState:UIControlStateSelected|UIControlStateDisabled];不会因任何原因导致崩溃。

这是导致与索引超出范围相关的崩溃的行[self.game cardAtIndex:[self.cardButtons indexOfObject:cardButton]];。基本上你有更多的cardButtons比self.game有卡片。

你可以用它来包装它以防止崩溃但是应该寻找更深层次的问题，为什么要创建一个额外的按钮。

int buttonIndex = [self.cardButtons indexOfObject:cardButton];
if (self.game.count > buttonIndex) {
    Card *card = [self.game cardAtIndex:buttonIndex];

    [cardButton setTitle:card.contents forState:UIControlStateSelected];

    [cardButton setTitle:card.contents forState:UIControlStateSelected|UIControlStateDisabled];

    cardButton.selected = card.isFaceUp;
    cardButton.enabled = !card.isUnPlayable;
}