隨機非重複編號Xcode

Question

對不起我的英文不好，我是阿根廷人。我有一個問題，我是一個瑣事應用程序，邏輯上它不必重新提問。我有30個問題，這是我的代碼：

-(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 _____"; 
    } 
} 

我想創建一個NSArray的地方，如果有一些誰重複，它再次洗牌。

我該怎麼辦？

Answer 1

你想要的實際上是一個NSMutableArray（因爲你會擴大它，因爲新值進來），並使用​​檢查以前選擇的值。預先警告，NSMutableArray存儲id類型的對象，並且int是一個原語。您需要將您的隨機值包裝在NSNumber中，然後才能存儲。是這樣的：

//.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

代替產生隨機數，並檢查是否該數字已被使用，我將創建的數字一個NSMutableArray 0至29（每個包裹在一個NSNumber），然後隨機洗牌數組使用由Gregory Goltsov在這個SO問題whats-the-best-way-to-shuffle-an-nsmutablearray中提供的類別。

然後，您只需從NSMutable數組的開始遍歷每個NSNumber對象。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，最好用一系列包含單個問題的問題和答案的對象填充數組。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 

編輯

我最初說Kristopher約翰遜的答案，但我真正的意思格雷戈裏Goltsov的回答

（Y英里西班牙語ES珥闕埃爾英語）

Answer 3

// 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]; 

}