Question

I was wondering if it is possible to add a second tag to a UIButton? I’ve created a number of buttons programatically in a for-loop and need a reference to the number of the button (e.g. 0, 1, 2) and another reference (integer) in which I store a reference to the page the button links to (e.g. 22, 30, 49). The numbers are not related so I can’t determine the first through the second.

This is what I’d like to have:

for (int k=0; k < numberOfTabs; k++) // k < 4 (e.g. 3 < 4) 
{
    UIButton* btn = [[[UIButton alloc] initWithFrame:frame] autorelease];
    btn.tag = k;

btn.tag2 = someReference;

    btn.frame = CGRectMake(-10, 0, buttonWidth, buttonHeight);
    [btn    addTarget:self
            action:@selector(tabAction:)
  forControlEvents:UIControlEventTouchUpInside];
    [btn    addTarget:self
                action:@selector(tabDelete:)
      forControlEvents:UIControlEventTouchDragOutside];
/...

Any suggestions would be very much appreciated.

Answer 1

Why not store the second (any more, if needed) parameters in something like an NSMutableArray?

NSMutableArray *button_to_page = [[NSMutableArray alloc] init];

...

for(...)
{

// Your button creation code

[button_to_page addObject:[NSNumber numberWithInt:my_button.tag];

}

You can get your page number at any time by simply indexing into the button_to_page array.
You can also search the array for a page number and get the button index (if needed).

Now, having said that, here you are creating a new NSNumber object for each button’s page tag and also carrying around an NSMutableArray to boot. I really think that subclassing UIButton is the way to go. I don’t like the idea of encoding stuff into the single tag unless there’s a real compelling reason. If you subclass you are still keeping the UIButton pretty lightweight and all your data is encapsulated within the same object very cleanly:

MultiTag_UIButton.h

#import <Foundation/Foundation.h>

@interface MultiTag_UIButton : UIButton {

}
@property (nonatomic, assign) int page;

@end

MultiTag_UIButton.m

#import "MultiTag_UIButton.h"

@implementation MultiTag_UIButton

@synthesize page;

@end

It really is that simple, you don’t have to write any code, just add the page property and you are off to the races. Then you can do this:

MultiTag_UIButton *test_button = [[MultiTag_UIButton alloc] init];

test_button.tag = 1;
test_button.page = 23;

NSLog(@"tag %i  page %i", test_button.tag, test_button.page);

[test_button release];

Clean and simple. Realistically you’d have to do a little more in the new class, but you get the idea.