Question

类“PlayingCardDeck”继承“Deck”类不能放方法

- (void) addCard:(Card *)card atTop:(BOOL)atTop

Xcode指责我出现以下错误：没有已知的选择器'addCard：atTop'

的类方法

课程：PlayingCardDeck

#import "PlayingCardDeck.h"
#import "PlayingCard.h"

@implementation PlayingCardDeck

- (id)init
{
    self = [super init];

    if(self) {
        for(NSString *suit in [PlayingCard validSuits]){
            for (NSUInteger rank = 1; rank <= [PlayingCard maxRank]; rank++){
                PlayingCard *card = [[PlayingCard alloc] init];
                card.rank = rank;
                card.suit = suit;
                [PlayingCardDeck addCard:card atTop:NO];
            }
        }
    }

    return self;
}

@end

课程：甲板

#import "Deck.h"

@interface Deck()

@property (strong, nonatomic) NSMutableArray *cards;

@end


@implementation Deck

- (NSMutableArray *)cards
{
    if(!_cards) _cards = [[NSMutableArray alloc] init];
    return _cards;
}

- (void) addCard:(Card *)card atTop:(BOOL)atTop
{
    if(atTop){
        [self.cards insertObject:card atIndex:0];
    } else {
        [self.cards addObject:card];
    }
}

- (Card *)drawRandomCard
{
    Card *randomCard = nil;

    if(self.cards.count){
        unsigned index = arc4random() % self.cards.count;
        randomCard = self.cards[index];
        [self.cards removeObjectAtIndex:index];
    }

    return randomCard;
}

@end

谢谢大家的帮助。

Answer 1

方法-addCard:atTop:是实例方法。它必须发送到类的实例，而不是类本身。这一行：

[PlayingCardDeck addCard:card atTop:NO];

正在尝试将其发送到类PlayingCardDeck，而不是该类的任何实例。这就是错误试图告诉你的。

由于该代码位于-init类的PlayingCardDeck方法中，您可能打算将邮件发送到self：

[self addCard:card atTop:NO];

使用方法时出错＆＃34;没有已知的选择器类方法＆＃34;

1 个答案: