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Object position ranking

I am making a small quiz app, but I have several problems.

I randomly ask questions from NSMutableArray using arc4random (), then I populate the view with three buttons, one containing the correct answer and the other 2 containing two incorrect answers

what I need to do is randomize the X coordinate (position) of the 3 buttons in the view, this is the code I am using, but this creates problems as it does not work as expected and the application is frequently reset when the action is called:

NSBundle *bundle02 = [NSBundle mainBundle];
NSString *textFilePath02 = [bundle02 pathForResource:@"possiblePositions" ofType:@"txt"];   
NSString *fileContents02 = [NSString stringWithContentsOfFile:textFilePath02 encoding:NSUTF8StringEncoding error:nil];
arrayPossiblePositions = [[NSMutableArray alloc] initWithArray:[fileContents02 componentsSeparatedByString:@"\n"]];

int length02 = [arrayPossiblePositions count];
int chosen02 = arc4random() % length02;
[arrayPossiblePositions removeObjectAtIndex:chosen02];
int chosen04 = arc4random() % length02;
[arrayPossiblePositions removeObjectAtIndex:chosen04];
int chosen05 = arc4random() % length02;

if ([questionString isEqualToString:@"question1"]) {

    buttonCorrect = [UIButton buttonWithType:UIButtonTypeCustom];
    CGRect newSize = CGRectMake(chosen02, 80, 130, 130);
    buttonCorrect.frame = newSize;
    [buttonCorrect setImage:[UIImage imageNamed:@"kncpf.png"] forState:UIControlStateNormal];
    [buttonCorrect addTarget:self action:@selector(answerCorrect) forControlEvents:UIControlEventTouchUpInside];
    [main addSubview:buttonCorrect];

    buttonUncorrect01 = [UIButton buttonWithType:UIButtonTypeCustom];
    CGRect newSize02 = CGRectMake(chosen04, 80, 130, 130);
    buttonUncorrect01.frame = newSize02;
    [buttonUncorrect01 setImage:[UIImage imageNamed:@"kncpf02.png"] forState:UIControlStateNormal];
    [buttonUncorrect01 addTarget:self action:@selector(answerUncorrect) forControlEvents:UIControlEventTouchUpInside];
    [main addSubview:buttonUncorrect01];

    buttonUncorrect02 = [UIButton buttonWithType:UIButtonTypeCustom];
    CGRect newSize034578 = CGRectMake(chosen05, 80, 130, 130);
    buttonUncorrect02.frame = newSize034578;
    [buttonUncorrect02 setImage:[UIImage imageNamed:@"kncpf034578.png"] forState:UIControlStateNormal];
    [buttonUncorrect02 addTarget:self action:@selector(answerUncorrect) forControlEvents:UIControlEventTouchUpInside];
    [main addSubview:buttonUncorrect02];
}

Can you suggest that I do something different because I am really going crazy?

Thanks in advance for your answers, David

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2 answers


I really needed to do something like this, but instead of moving images around, I decided to do this instead:

  • Create three buttons where you want them to appear (given locations).
  • Assign images to each button arbitrarily (by randomizing NSMutableArray with NSStrings of image names).
  • Instead of assigning @selector (answerCorrect) and @selector (answerUncorrect) assign @selector (checkIfCorrect :)
  • Define checkIfCorrect as such:

- (void) checkIfCorrect: (id) sender {UIImage * buttonImage = sender.image;

if (buttonImage == [UIImage imageNamed: @ "kncpf.png"]) {[self answerCorrect]; } else {[self answerIncorrect]; }

}

CHANGE THE CODE WHICH I RECOMMEND:

Also, you call



int length02 = [arrayPossiblePositions count];
int chosen02 = arc4random() % length02;
[arrayPossiblePositions removeObjectAtIndex:chosen02];
int chosen04 = arc4random() % length02;
[arrayPossiblePositions removeObjectAtIndex:chosen04];
int chosen05 = arc4random() % length02;

Note that length02 remains unchanged, but arrayPossiblePositions is resized. This is probably the first reason your code is failing: you are trying to remove an index from an array that is outside the array!

I haven't tested but should work: (don't forget to define checkanswer () as I mentioned above)

NSMutableArray *imagesArray = [NSMutableArray arrayWithObjects:@"image1.png", @"image2.png", @"image3.png", nil];

int count1 = [imagesArray count];
int index1 = arc4random() % count1;

button1 = [UIButton buttonWithType:UIButtonTypeCustom];
    CGRect newSize = CGRectMake(30, 80, 130, 130);
    button1.frame = newSize;
    [button1 setImage:[UIImage imageNamed:[imagesArray objectAtIndex:index1]] forState:UIControlStateNormal];
    [button1 addTarget:self action:@selector(checkAnswer:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button1];

[imagesArray removeObjectAtIndex:index1];
int count2 = [imagesArray count];
int index2 = arc4random() % count2;

button2 = [UIButton buttonWithType:UIButtonTypeCustom];
    CGRect newSize = CGRectMake(160, 80, 130, 130);
    button2.frame = newSize;
    [button2 setImage:[UIImage imageNamed:[imagesArray objectAtIndex:index2]] forState:UIControlStateNormal];
    [button2 addTarget:self action:@selector(checkAnswer:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button2];

[imagesArray removeObjectAtIndex:index2];
int count3 = [imagesArray count];
int index3 = arc4random() % count3;

button3 = [UIButton buttonWithType:UIButtonTypeCustom];
    CGRect newSize = CGRectMake(290, 80, 130, 130);
    button3.frame = newSize;
    [button3 setImage:[UIImage imageNamed:[imagesArray objectAtIndex:index3]] forState:UIControlStateNormal];
    [button3 addTarget:self action:@selector(checkAnswer:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button3];
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I think arc4random () needs upper bounds. Not sure if using a module is correct here, or rather a semantic error, not sure how an arc reacts when you try to perform an operation like this without setting its upper bounds first. I'm not sure, try subbing on a hard value instead of your length02 and see if you get the expected behavior then lean back.



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