Question

抱歉我的英语不好，我是阿根廷人。我有一个问题，我是一个琐事应用程序，从逻辑上讲它不需要再问同样的问题。我有30个问题，这是我的代码：

-(IBAction)randomear{
    random1=arc4random() % 30;
    if (random1 == 0)
    {
        labelpregunta.text = @"Las ovejas pueden nadar?";
    }
    if (random1 == 1)
    {
        labelpregunta.text = @"Con que se tiñe la lana de negro?";
    }
    if (random1 == 2)
    {
        labelpregunta.text = @"De que material es el mejor casco?";
    }
    if (random1 == 3)
    {
        labelpregunta.text = @"Para fabricar lana necesitas 4 _____";
    }
}

我想创建一个NSArray，如果有一个重复的数字，它会再次洗牌。

我该怎么做？

Answer 1

您想要的实际上是NSMutableArray（因为您将在新值出现时将其展开），并使用-indexOfObject检查以前选择的值。预先警告，NSMutableArray存储类型为id的对象，而int是基元。在存储之前，您需要将随机值包装在NSNumber中。像这样：

//.h
@property (nonatomic, strong) NSMutableArray *previouslySelectedValues;

//.m
-(IBAction)randomear{
    //I suppose this is an int, right?
    //Supongo que esto es un número entero.
    random1=arc4random() % 30;
    //check if the array can find the object.  It internally uses `-isEqual` in a loop for us
    //estamos comprobando si la matriz se puede encontrar el objeto
    if (![previouslySelectedValues indexOfObject:[NSNumber numberWithInt:random1]]) {
        if (random1 == 0)
        {
            labelpregunta.text = @"Las ovejas pueden nadar?";
        }
        if (random1 == 1)
        {
            labelpregunta.text = @"Con que se tiñe la lana de negro?";
        }
        if (random1 == 2)
        {
            labelpregunta.text = @"De que material es el mejor casco?";
        }
        if (random1 == 3)
        {
            labelpregunta.text = @"Para fabricar lana necesitas 4 _____";
        }

        //et cetera/ etcétera

        //add the object because it doesn't exist and we don't want to select it again.
        //Añadir el objeto a la matriz debido a que es nuevo
        [previouslySelectedValues addObject:[NSNumber numberWithInt:random1]];
    }
    else {
        //do nothing, or use the below pick again if you want
        //No hacer nada, o utilizar el método de abajo para elegir otro número

        //[self randomear];
        return;
    }
}

Answer 2

    // You store your strings here
    static NSArray *myQuestions = [[NSArray alloc] initWithObjects:
                                          @"Las ovejas pueden nadar?",
                                          @"Con que se tiñe la lana de negro?",
                                          @"De que material es el mejor casco?",
                                          @"Para fabricar lana necesitas 4 _____",nil];
    // Make a copy which is mutable
    NSMutableArray *copy = [NSMutableArray arrayWithArray:myQuestions];
    ...

-(IBAction)randomear{

    // Now select one entry
    random1=arc4random() % [copy count];
    labelpregunta.text = [copy objectAtIndex:random1];
    [copy removeObjectAtIndex:random1];

}

Answer 3

我没有生成一个随机数并检查是否已使用该数字，而是创建一个数字0到29的NSMutableArray（每个包裹在一个NSNumber中），然后随机地重新排列数组使用Gregory Goltsov在此SO问题whats-the-best-way-to-shuffle-an-nsmutablearray中提供的类别。

然后，您只需从NSMutable数组的开头迭代每个NSNumber对象。即。

#import "NSMutableArray_Shuffling.h // From Gregory Goltsov
NSMutableArray* randomNumbers = [[NSMutableArray alloc] init];
for(int i=0; i<30; i++) {
  [randomNumbers addObject:[NSNumber numberWithInt:i]];
}
[randomNumbers shuffle]; // From Gregory Goltsov

...

int lastIndex = 0;

-(IBAction)randomear
{
    if (lastIndex<30) {
        NSNumber* theRandomNumber = [randomNumbers objectAtIndex:lastIndex];
        int theQuestion = [theRandomNumber intValue];
        if (theQuestion == 0)  {
            labelpregunta.text = @"Las ovejas pueden nadar?";
        }
        if (theQuestion == 1) {
            labelpregunta.text = @"Con que se tiñe la lana de negro?";
        }
        if (theQuestion == 2) {
            labelpregunta.text = @"De que material es el mejor casco?";
        }
        if (theQuestion == 3){
            labelpregunta.text = @"Para fabricar lana necesitas 4 _____";
        }

        //et cetera/ etcétera    
        lastIndex++;
    } else {
        // No more questions
    }
}

但是，最好用一系列包含单个问题的问题和答案的对象填充数组。即。

@interface aQuestion : NSObject
@property (nonatomic, string) NSString* question;
@property (nonatomic, string) NSString* answer;
-(void)initWithQuestion:(NSString)aQuestion and:(NSString) anAnswer;
-(BOOL)isCorrectAnswer(NSString testAnswer);
@end

@implementation aQuestion
-(void)initWithQuestion:(NSString*)aQuestion and:(NSString*) anAnswer
{
  if(!(self=[super init])) return self;

  question = aQuestion;
  answer = anAnswer;

  return self;
}

-(BOOL)isCorrectAnswer(NSString testAnswer)
{
  [answer isEqualToString:testAnswer];
}
@end

...
#import "NSMutableArray_Shuffling.h // From Gregory Goltsov
NSMutableArray* questions = [[NSMutableArray alloc] init];

[questions addObject:[[aQuestion alloc] initWithQuestion:@"Question 1" and:@"Answer 1"]];
[questions addObject:[[aQuestion alloc] initWithQuestion:@"Question 2" and:@"Answer 2"]];
[questions addObject:[[aQuestion alloc] initWithQuestion:@"Question 3" and:@"Answer 3"]];
[questions addObject:[[aQuestion alloc] initWithQuestion:@"Question 4" and:@"Answer 4"]];
[questions shuffle]; // From Gregory Goltsov

...
for(int i=0; i<[questions count]; i++) {
   aQuestion* theQuestion = [questions objectAtIndex:i];

   // Ask theQuestion.question
   labelpregunta.text = theQuestion.question;

   ...

   // wait for theAnswer

   ....

   NSString theAnswer = labelrespuesta.text;

   if ([theQuestion isCorrectAnswer:theAnswer]) {
      // You win!!!!!!!
   }
}

// No more questions

修改

我最初说克里斯托弗·约翰逊的回答，但我真的是指格雷戈里·戈尔佐夫的回答

（Ymiespañolespeor queelInglés）

随机非重复数字Xcode

3 个答案: