我正在尝试创建一个简单的应用程序，允许您从卡组中挑选一张卡片。我需要它做的是不要重复相同的卡。我看过整个互联网，我不清楚如何做到这一点。
以下是我现在的代码：
-(IBAction) randomize: (id)sender {
int randomcards = rand() % 53 + 1;
switch (randomcards) {
case 0:
imageview.image = [UIImage imageNamed:@"1.png"];
break;
case 1:
imageview.image = [UIImage imageNamed:@"2.png"];
break;
case 2:
imageview.image = [UIImage imageNamed:@"3.png"];
break;
case 3:
imageview.image = [UIImage imageNamed:@"4.png"];
break;
case 4:
imageview.image = [UIImage imageNamed:@"5.png"];
break;
case 5:
imageview.image = [UIImage imageNamed:@"6.png"];
break;
case 6:
imageview.image = [UIImage imageNamed:@"7.png"];
break;
case 7:
imageview.image = [UIImage imageNamed:@"8.png"];
break;
case 8:
imageview.image = [UIImage imageNamed:@"9.png"];
break;
case 9:
imageview.image = [UIImage imageNamed:@"10.png"];
break;
case 10:
imageview.image = [UIImage imageNamed:@"11.png"];
break;
case 11:
imageview.image = [UIImage imageNamed:@"12.png"];
break;
case 12:
imageview.image = [UIImage imageNamed:@"13.png"];
break;
case 13:
imageview.image = [UIImage imageNamed:@"14.png"];
break;
case 14:
imageview.image = [UIImage imageNamed:@"15.png"];
break;
case 15:
imageview.image = [UIImage imageNamed:@"16.png"];
break;
case 16:
imageview.image = [UIImage imageNamed:@"17.png"];
break;
case 17:
imageview.image = [UIImage imageNamed:@"18.png"];
break;
case 18:
imageview.image = [UIImage imageNamed:@"19.png"];
break;
case 19:
imageview.image = [UIImage imageNamed:@"20.png"];
break;
case 20:
imageview.image = [UIImage imageNamed:@"21.png"];
break;
case 21:
imageview.image = [UIImage imageNamed:@"22.png"];
break;
case 22:
imageview.image = [UIImage imageNamed:@"23.png"];
break;
case 23:
imageview.image = [UIImage imageNamed:@"24.png"];
break;
case 24:
imageview.image = [UIImage imageNamed:@"25.png"];
break;
case 25:
imageview.image = [UIImage imageNamed:@"26.png"];
break;
case 26:
imageview.image = [UIImage imageNamed:@"27.png"];
break;
case 27:
imageview.image = [UIImage imageNamed:@"28.png"];
break;
case 28:
imageview.image = [UIImage imageNamed:@"29.png"];
break;
case 29:
imageview.image = [UIImage imageNamed:@"30.png"];
break;
case 30:
imageview.image = [UIImage imageNamed:@"31.png"];
break;
case 31:
imageview.image = [UIImage imageNamed:@"32.png"];
break;
case 32:
imageview.image = [UIImage imageNamed:@"33.png"];
break;
case 33:
imageview.image = [UIImage imageNamed:@"34.png"];
break;
case 34:
imageview.image = [UIImage imageNamed:@"35.png"];
break;
case 35:
imageview.image = [UIImage imageNamed:@"36.png"];
break;
case 36:
imageview.image = [UIImage imageNamed:@"37.png"];
break;
case 37:
imageview.image = [UIImage imageNamed:@"38.png"];
break;
case 38:
imageview.image = [UIImage imageNamed:@"39.png"];
break;
case 39:
imageview.image = [UIImage imageNamed:@"40.png"];
break;
case 40:
imageview.image = [UIImage imageNamed:@"41.png"];
break;
case 41:
imageview.image = [UIImage imageNamed:@"42.png"];
break;
case 42:
imageview.image = [UIImage imageNamed:@"43.png"];
break;
case 43:
imageview.image = [UIImage imageNamed:@"44.png"];
break;
case 44:
imageview.image = [UIImage imageNamed:@"45.png"];
break;
case 45:
imageview.image = [UIImage imageNamed:@"46.png"];
break;
case 46:
imageview.image = [UIImage imageNamed:@"47.png"];
break;
case 47:
imageview.image = [UIImage imageNamed:@"48.png"];
break;
case 48:
imageview.image = [UIImage imageNamed:@"49.png"];
break;
case 49:
imageview.image = [UIImage imageNamed:@"50.png"];
break;
case 50:
imageview.image = [UIImage imageNamed:@"51.png"];
break;
case 51:
imageview.image = [UIImage imageNamed:@"52.png"];
break;
case 52:
imageview.image = [UIImage imageNamed:@"53.png"];
break;
case 53:
imageview.image = [UIImage imageNamed:@"54.png"];
break;
}
任何人都可以给我一些明确的指示，说明在牌组用完之前如何阻止同一张牌出现两次？我将不胜感激。
答案 0 :(得分：4)
不是挑选随机卡，而是将所有卡分配到一个数组中，然后随机播放阵列。之后，您可以遍历数组，从而随机选择卡片。
请参阅此问题whats-the-best-way-to-shuffle-an-nsmutablearray
看看Gregory Goltsov使用arc4random_uniform（）的答案
答案 1 :(得分：1)
使用您所有图片的名称（或用于指示唯一卡片的任何图片）预加载阵列。
对于每张卡：根据阵列中剩余的卡数计算随机数，选择卡，从阵列中删除其参考。
答案 2 :(得分：0)
正如其他人所指出的，最简单的方法是创建一个图像名称数组并删除已经使用过的名称。这是一个例子。在标题中声明这样的属性。
@property (strong, nonatomic) NSMutableArray *availableCards;
在实施的顶部合成它。
@synthesize availableCards = _availableCards;
使用方便的方法让你初始化/重置它。
- (void) resetAvailableCards {
NSMutableArray *resetArray = [[NSMutableArray alloc] init];
//the temporary array to store what we'll set our property to at the end
for (int i = 1; i < 55; ++i){//for every card in the deck
NSString* imageName = [NSString stringWithFormat:@"%d.png",i];//make the image name
[resetArray addObject:imageName];//store it in the array
}
self.availableCards = resetArray;//set our property to the array
}
在控制器的viewDidLoad中调用它以初始化状态。
[self resetAvailableCards];
您还可以在需要再次使用所有卡时调用它。现在，为您的原始方法。
- (IBAction) randomize: (id) sender {
int cardIndex = arc4random() % [self.availableCards count];//random number within the bounds of the array; no need to add 1 as count is 1 higher than highest available index
NSString* cardImageName = [self.availableCards objectAtIndex: cardIndex];//get the name of the card we chose
imageview.image = [UIImage imageNamed: cardImageName];//set the image
[self.availableCards removeObjectAtIndex:cardIndex];//remove the card name so we can't get it again
return;
}
注意我使用的是arc4random而不是rand。它具有两倍的有效范围，并且倾向于提供更好的分布以及不需要播种。如果您想有效地使用rand，则需要使用srand为时间或其他内容播种。我还建议你删除动作中的sender参数，因为它没有被使用，虽然你也必须在其他地方更改它，所以你可能想把它保留。
只是想知道，但是imageview是什么？既然你没有使用self.imageview，那它是一个伊娃吗？它是一个属性，你忘了使用点符号，并直接访问ivar支持它？无论哪种方式，您都应该将其声明为某种属性/出口，并通过访问器访问它。