I want to select 6 random buttons out of fifty

Question

I'm trying to create an iPhone application in which I have 50 buttons, numbered 1 to 50.

Now, I want to select any 6 out of 50 random buttons and it's value(numbers).

My questions are,

How can I only select 6 buttons?
Right now I'm thinking of taking 50 different IBOutlets and 50 IBActions respectively for each button to achieve my purpose. Is there any other better alternative that I can go for like an Array of Button?
How do I retrieve the value of particular button?

It isn't quite clear what you mean. How many buttons will be displayed at once? What is the difference between the buttons? What happens when they are tapped? — jrturton, Nov 15 '11 at 12:14
yes you can create NSArray or NSMutableArray to store your 50 buttons.. — Maulik, Nov 15 '11 at 12:16
@jrturton, sorry for the trouble but here are the answers for your questions. Basically there ll be 1 to 50 numbers as a buttons on a screen from which user can select 6 numbers only. all the buttons are named as a number 1 to 50. when user taps on six random buttons each buttons value should be stored in one single string. — MayurCM, Nov 17 '11 at 09:31

score 3 · Answer 1 · edited May 23 '17 at 12:29

3

You could create the buttons programmatically like this ( add them as subviews to a container view): How do I create a basic UIButton programmatically?

You can keep the number of the button in its tag propery.

To select a button with a given tag use [containerView viewWithTag:(NSInteger)].

To select 6 different random views you need to generate 6 different random numbers and use the above method.

You could do it like this.

bool used[51];
for (int i = 1 ; i <= 50 ; ++i)
    used[i] = false;
int count = 0;
int resulttags[6];
while (count < 6) {
    int index = 1 + random() % 50;
    if (!used[index]) {
         used[index] = true;
         resulttags[count++] = index;
    }
}

edited May 23 '17 at 12:29

Community

1
1

answered Nov 15 '11 at 12:17

silviupop

638
7
14

You should use arc4random() instead random() - http://iphonedevelopment.blogspot.com/2008/10/random-thoughts-rand-vs-arc4random.html – Eugene Nov 15 '11 at 12:22
Why use the tag, when you just can keep the object? – vikingosegundo Nov 15 '11 at 14:03

vikingosegundo · Answer 2 · 2011-11-15T15:22:48.820

Create a loop in which you create 50 Buttons and store them in an mutable array.

Shuffle the array, best by crating a category on NSMutableArray and pick the first 6 objects from it.
You'll find a Category with several convenient methods in my arraytools

One important information is missing: How do the methods the buttons should trigger, look like?
If you have something regular like -pressedButton<No>:, the for-loop could look like:

create and store 50 buttons

self.buttons = [NSMutableArray arrayWithCapacity:50]; //NSMutableArray

for (int i=0; i<50, i++)
{
    UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [button addTarget:self 
               action:@selector(NSSelectorFromString([NSString stringWithFormat:@"pressedButton%i:", i]))
     forControlEvents:UIControlEventTouchDown];

    [buttons addObject:button];
}

shuffle and pick 6 buttons

[buttons shuffle]; // see arraytools
NSArray *sixButtons = [buttons objectsAtIndexes:[NSIndexSet indexSetWithIndexesInRange:NSMakeRange(0,6)]];

and finally calculate a frame for each button in sixButtons, and add it to the designated view [view addSubview:button];

If you don't have a method for every Button, you can distinguish the buttons by their indexes within the buttons array. But be careful: In this case you shouldn't shuffle it. Instead you should transform it int an unmutable array

NSMutableArray *buttonsTemp = [NSMutableArray arrayWithCapacity:50];

for (int i=0; i<50, i++)
{
    UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [button addTarget:self 
               action:@selector(buttonPressed:)
     forControlEvents:UIControlEventTouchDown];

    [buttonsTemp addObject:button];
}

self.buttons = [NSArray arrayWithArray:buttonsTemp]; //Member of type NSArray

Now you can pick 6 buttons randomly

NSSet *sixButtos = [buttons setWithRandomElementsSize:6];//see arraytools

-buttonPressed: could be like this:

-(void) buttonPressed:(UIButton *)sender
{
     NSUInteger buttonIndex = [buttons indexOfObject:sender];
     //Now you can use if or switch to distinguish, what needs to be done

}

I want to select 6 random buttons out of fifty

2 Answers2