重新启动目标 c 中的对象 - Matchismo 作业 2 - 重新开始游戏答案

【问题标题】：restart object in objective c - Matchismo Assignment 2 - Restart game重新启动目标 c 中的对象 - Matchismo 作业 2 - 重新开始游戏
【发布时间】：2014-05-23 13:27:21
【问题描述】：

我正在尝试解决斯坦福 iOS7 开发（Matchismo 纸牌游戏）的作业 2

游戏运行良好。现在我必须添加重启功能。如果用户按下重启按钮，游戏会重启（它会发新牌并重置分数）

我的游戏模型是@property (nonatomic, strong) CardMatchingGame *game;

这是 CardMatchingGame.m 的代码：

#import "CardMatchingGame.h"
#import "PlayingCardDeck.h"




@interface CardMatchingGame()
@property (nonatomic, readwrite) NSInteger score;
@property (nonatomic, strong) NSMutableArray *cards;
@end

@implementation CardMatchingGame


static const int MATCH_BONUS = 4;
static const int MATCH_PENALTY = 2;
static const int COST_TO_CHOOSE = 1;

-(NSMutableArray *)cards{
    if(!_cards) _cards = [[NSMutableArray alloc]init];
    return _cards;
}
-(instancetype)initWithCardCount:(NSUInteger)count usingDeck:(Deck *)deck{
    self = [super init];

    if(self){
        for(int i=0; i < count; i++){
            Card *card = [deck drawRandomCard];
            if(card){
                [self.cards addObject:card];
            } else{
                self = nil;
                break;
            }
        }
    }

    return self;
}

-(void)chooseCardAtIndex:(NSUInteger)index{
    Card *card = [self cardAtIndex:index];
    if(!card.isMatched){
        if(card.isChosen){
            card.chosen = NO;
        } else{
            for(Card *otherCard in self.cards){
                if(otherCard.isChosen && !otherCard.isMatched){
                    int matchScore = [card match:@[otherCard]];
                    if(matchScore){
                        self.score += matchScore * MATCH_BONUS;
                        card.matched = YES;
                        otherCard.matched = YES;
                    } else{
                        self.score -= MATCH_PENALTY;
                        otherCard.chosen = NO;

                    }
                    break;
                }
            }
            self.score -= COST_TO_CHOOSE;
            card.chosen = YES;

        }
    }

}

-(Card *)cardAtIndex:(NSUInteger)index{
    return (index < [self.cards count]) ? self.cards[index] : nil;
}


@end

这是我的 CardGameViewController.m：

#import "CardGameViewController.h"
#import "PlayingCardDeck.h"
#import "CardMatchingGame.h"

@interface CardGameViewController ()


@property (nonatomic, strong) Deck *deck;

@property (nonatomic, strong) CardMatchingGame *game;

@property (strong, nonatomic) IBOutletCollection(UIButton) NSArray *cardsCollection;

@property (weak, nonatomic) IBOutlet UILabel *scoreLabel;
@end

@implementation CardGameViewController
@synthesize game = _game;

-(CardMatchingGame *)game{
    if(!_game) _game = [[CardMatchingGame alloc] initWithCardCount:[self.cardsCollection count]
                                                         usingDeck:self.deck];
    return _game;
}

-(Deck *)deck{
    if(!_deck) _deck = [[PlayingCardDeck alloc] init];
    return _deck;
}
- (IBAction)touchRestartButton:(id)sender {
    self.game = nil;
    [self updateUI];
}

- (IBAction)touchCardButton:(UIButton *)sender {
    int chosenButtonIndex = [self.cardsCollection indexOfObject:sender];
    [self.game chooseCardAtIndex:chosenButtonIndex];
    [self updateUI];





}
-(void)updateUI{
   for(UIButton *cardButton in self.cardsCollection){
        int buttonIndex = [self.cardsCollection indexOfObject:cardButton];
        Card *card = [self.game cardAtIndex:buttonIndex];
        [cardButton setTitle:[self titleForCard:card] forState:UIControlStateNormal];
        [cardButton setBackgroundImage:[self backgroundImageForCard:card] forState:UIControlStateNormal];
        cardButton.enabled = !card.isMatched;
    }
    self.scoreLabel.text = [NSString stringWithFormat:@"Score: %d", self.game.score];
}
-(NSString *)titleForCard:(Card *)card{
    return card.isChosen ? card.contents : @"";
}
-(UIImage *)backgroundImageForCard:(Card *)card{
    return [UIImage imageNamed: card.isChosen ? @"cardfront" : @"cardback"];

}

@end

为了重新开始游戏，我想我应该简单地重新初始化属性 CardMatchingGame *game。

这是我尝试做的，通过设置self.game = nil; 然后它应该在游戏的getter中自动重新初始化。

这确实是我在互联网上找到的解决方案。但是，在我的程序中它不起作用。 *游戏设置为 nil 并且从不恢复，所以当你点击重启时游戏结束。

您能帮我弄清楚为什么self.game = nil 在我的情况下不起作用吗？

【问题讨论】：

为什么不自己重新初始化呢？
我该怎么做？抱歉，这是我第一次使用 Objective C
self.game = [[CardMatchingGame alloc] initWithCardCount:[self.cardsCollection count] usingDeck:self.deck];
不幸的是，这也不起作用

标签： ios objective-c initialization null

【解决方案1】：

- (IBAction)startover:(UIButton *)sender {

    self.game= [[CardMatchingGame alloc] initWithCardCount:[self.cardButtons count] usingDeck:[self createDeck]];

    [self updateUI];
}

【讨论】：

【解决方案2】：

如果你的程序有推荐的惰性初始化风格，就不需要重新开始等新方法。您将 self.game 设置为 nil 是正确的，现在调用 getter 将启动游戏的新实例。我通过在 self.game = nil 之后立即调用 UIUpdate 来做到这一点。这会调用 getter 并懒惰地初始化游戏的新实例。

【讨论】：