Is there any alternative to use like tag to property of UIView? The thing is I'd like to pass UITextField some NSInteger. Way to do is tag. But I want to pass 2 different NSInteger.

Any ideas?

• iphone
• objective-c
• uiview
• tags

You could subclass UITextField and add two NSInteger properties to the class.

@interface CustomTextField : UITextField

@property (nonatomic, assign) NSInteger x;
@property (nonatomic, assign) NSInteger y;

@end

You can attach any data to any object using an Associative Reference. This is a very handy approach. It even correctly handles memory management. I sometimes use a category to wrap these so I can create new properties on an existing class. For example, in one project I'd like every view controller to know about a special label (like how they all know about navigationController). I do it this way:

@interface UIViewController (MYSpecialViewController)
@property (nonatomic, readwrite, strong) UILabel *specialLabel;
@end

@implementation UIViewController (MYSpecialViewController)
static const char kMySpecialLabelKey;

- (UILabel *)specialLabel
{
  return objc_getAssociatedObject(self, &kMySpecialLabelKey);
}

- (void)setSpecialabel:(UILabel *)value
{
  objc_setAssociatedObject(self, &kMySpecialLabelKey, value, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
@end

You can find a simple working example using a UIAlertView in the iOS5:PTL sample code for Chapter 3.

Take the general, object-oriented solution, but remember you can a stuff lot of data into a tag:

- (uint32_t)pack:(uint16_t)a with:(uint16_t)b {

  return (uint32_t)(a << 16 | b);
}

- (uint16_t)getA:(uint32_t)pair {
    return (uint16_t)((pair & 0xffff0000) >> 16);
}

- (uint16_t)getB:(uint32_t)pair {
    return (uint16_t)(pair & 0xffff);
}

// use it

- (void)setupSomeView {

    someView.tag = [self pack:1024 with:2048];
}

- (IBAction)someControlEventHappened:(id)sender {

    NSLog(@"%d %d", [self getA:sender.tag], [self getB:sender.tag]);
}

Caveats:

1. @RobNapier's answer is more general, more correct. The only advantage this way is that it's quick and dirty
2. Works for pairs of unsigned ints < 32k
3. Works NSInteger implementations >= 32 bits, which is everywhere, I think.