Deck

• .h

#import <Foundation/Foundation.h>
@interface Deck : NSObject
- (void)addCard:(Card *)card;
- (void)addCard:(Card *)card atTop:(Bool)atTop;
- (Card *)drawRandomCard;
@end

• .m

#import "Deck.h"
@interface Deck()
@property (strong, nonatomic) NSMutableArray *cards;
@end
@implementation Deck
  
//一開始 cards 實例變量是 nil，要重寫 getter 來初始化
- (NSMutableArray *)cards {
    //惰性初始化，即當要使用該變量時才初始化
    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];
    }
}
- (void)addCard:(Card *)card {
    [self addCard:card atTop:NO];
}

- (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

PlayingCard

• .h

  #import "Card.h"
  @interface PlayingCard: Card
  @property (strong, nonatomic) NSString *suit;
  @property (nonatomic) NSUInteger rank;
  + (NSArray *)validSuits;
  + (NSUInteger)maxRank;
  //外部只需要知道最大牌點是多少，而不需要知道詳細有什么牌
  @end
  

• .m

  #import "PlayingCard.h"
  @implementation PlayingCard
  - (NSString *)contents {
        NSArray *rankStrings = [self rankStrings];
        return [rankStrings[self.rank] stringByAppendingString:self.suit]; 
  }
  
  + (NSArray *)rankStrings {
        return @[@"?", @"A", @"2", @"3", @"4", @"5", @"6", @"7", @"8", @"9", @"10", @"J", @"Q", @"K"];
  }
  
  + (NSArray *)validSuits {
        return @[@"??", @"??", @"??", @"??"];
  }
  //上述兩個類方法不會影響性能，只是為了可讀性
  
  + (NSUInteger)maxRank { return [[self rankStrings] count]-1; }
  
  - (void)setRank:(NSUInteger)rank {
        if (rank M= [PlayingCard maxRank]) {
            _rank = rank;
      }
  }
  @synthesize suit = _suit;
  //同時重寫 setter 和 getter 時必須手寫 synthesize
  - (void)setSuit:(NSString *)suit {
        if ([validSuits containsObject:suit]) {
            _suit = suit;
      }
  }
  
  - (NSString *)suit {
        return _suit? : _suit : @"?";
  }
  @end
  

PlayingCardDeck

• .h

  import "Deck.h"
  
  @interface PlayingCardDeck : Deck
  @end
  

• .m

  #import "PlayingCardDeck.h"
  #import "PlayingCard.h"
  @implementation Deck
  - (instancetype)init {
        //instancetype 是 NSObject 中規(guī)定的 init 的返回值
        //它的意思是這個返回的對象和這個消息將要發(fā)送給的對象是同一類型的
    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;
                    [self addCard: card]; 
              }
          }
      }
        return self;
  }
  @end
  

CardGameViewController

IBAction 和 IBOutlet 實際上都是 typedef void

只是為了方便 xcode，編譯時會忽略