Question

I need to generate a grid of buttons for an iOS app. Each button needs two parameters: the number of the column and the number of the row. A button will also have two states, activated and deactivated.

When the app is loaded I want there to be like 21 rows and 16 columns. And somewhere on the screen there will also be a button that says “add columns” and this would add 4 extra columns every time it’s clicked.

Any suggestions how I should do this? I could start by adding the first 21*16 buttons with the IB but will that allow me to extend it with extra columns later on, and how?

Edit: the bounty was only started to reward mbm30075, no new answers necessary

Answer 1

I believe this is a more complete solution. Here’s the .h/.m pair I wrote up for testing:

ViewController.h

#import <UIKit/UIKit.h>
@interface ViewController : UIViewController 
@property (assign, nonatomic) int numColumns;
@property (assign, nonatomic) int numRows;
@property (strong, nonatomic) NSMutableArray *buttonsArray;
@property (strong, nonatomic) IBOutlet UIScrollView *scrollView;
@property (strong, nonatomic) IBOutlet UIButton *addButtons;
@property (strong, nonatomic) IBOutlet UIView *buttonsView;
- (IBAction)addFourMoreColumns;
@end

ViewController.m

#import "ViewController.h"
@implementation ViewController
@synthesize addButtons;
@synthesize buttonsArray;
@synthesize buttonsView;
@synthesize numColumns;
@synthesize numRows;
@synthesize scrollView;
- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    [self setButtonsArray:[NSMutableArray array]];
    [self setNumColumns:16];
    [self setNumRows:21];
    [self layoutButtons];
}
- (void)layoutButtons {
    static int width  = 100;
    static int height = 37;
    static int buffer = 8; // space between buttons (horiz. & vert.)
    static int margin = 20;
    CGPoint topLeft = CGPointMake(margin,margin); // standard "top left" in iOS
    // Since you appear to be wanting to modify the number of columns,
    // I'm going to make the multi-dimension array an array of columns, 
    // with each column containing an array of buttons (representing the rows)

    // Iterate through how many columns SHOULD exist ([self numColumns])
    for (int i = 0; i < [self numColumns]; i = i + 1) {
        // Check if this "column" exists (does this index exist in [self buttonsArray]?)
        if (i >= [[self buttonsArray] count]) {
            // It doesn't exist, so we need to add a blank array
            [[self buttonsArray] addObject:[NSMutableArray array]];
        }
        NSMutableArray *column = [[self buttonsArray] objectAtIndex:i];
        // Now, we iterate through how many rows/buttons SHOULD exist ([self numRows])
        for (int j = 0; j < [self numRows]; j = j + 1) {
            // Check if this "row"/"cell"/"button" exists
            if (j >= [column count]) {
                // It doesn't exist, so we need to add a new button AND PLACE IT!
                // Of course, you need to make your button type correctly
                // This is just standard button code...
                UIButton *btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
                [btn setFrame:CGRectMake(topLeft.x,topLeft.y,width,height)];
                // Do whatever else you need to do with the button...
                // Set title...
                [btn setTitle:[NSString stringWithFormat:@"(%d,%d)", i + 1, j + 1] forState:UIControlStateNormal];
                // Add target actions...
                [btn addTarget:self action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside];
                // Add the button to the view
                [[self buttonsView] addSubview:btn];
                // Add the button to the array
                [column addObject:btn];
            }
            // Increment topLeft to the next "row" for correct button placement...
            topLeft = CGPointMake(topLeft.x, topLeft.y + height + buffer);
        }
        // Increment topLeft to the next "column" for correct button placement...
        topLeft = CGPointMake(topLeft.x + width + buffer, margin);
    }
    // So, I'm assuming your "add columns" button will be placed equivalent to 
    // "(columnCount + 1, 1)", or at the top of the screen, just to the right
    // of the right-most column of buttons
    // [self addButtons] is the property to the UIButton that calls [self addFourMoreColumns]
    [[self addButtons] setFrame:CGRectMake(topLeft.x, topLeft.y, [[self addButtons] frame].size.width, [[self addButtons] frame].size.height)];
    // Now, update the view that holds the buttons to give it a new size (based on the buttons added)
    CGRect viewFrame = CGRectMake(0, 0, CGRectGetMaxX([[self addButtons] frame]) + buffer, 20 + ([[self buttonsArray] count] * (height + buffer)));
    [[self buttonsView] setFrame:viewFrame];
    [[self scrollView] setContentSize:viewFrame.size];
    // Redraw the view...
    [[self view] setNeedsDisplay];
}
- (IBAction)addFourMoreColumns {
    [self setNumColumns:[self numColumns] + 4];
    [self layoutButtons];
}
// Shows in the log which button you pressed: "(col, row)"
- (void)buttonPressed:(id)sender {
    for (int i = 0; i < [[self buttonsArray] count]; i = i + 1) {
        NSMutableArray *col = [[self buttonsArray] objectAtIndex:i];
        for (int j = 0; j < [col count]; j = j + 1) {
            if (sender == [col objectAtIndex:j]) {
                NSLog(@"button (%d,%d) pressed", i + 1, j + 1);
                break;
            }
        }
    }
}
@end

Xib setup is basic with:

View                 // tied to [ViewController view]
|
--->ScrollView       // tied to [ViewController scrollView]
    |
    --->View         // tied to [ViewController buttonsView]
        |
        --->UIButton // tied to [ViewController addButtons]