How to make and use first object in Objective C to store sender tag

Posted by dbonneville on Stack Overflow See other posts from Stack Overflow or by dbonneville
Published on 2010-03-25T02:24:08Z Indexed on 2010/03/25 2:33 UTC
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I started with a sample program that simply sets up a UIView with some buttons on it. Works great.

I want to access the sender tag from each button and save it. My first thought was to save it to a global variable but I couldn't get it to work right.

I thought the best way would be to create an object with one property and synthesize it so I can get or set it as needed.

First, I created GlobalGem.h:

#import <Foundation/Foundation.h>

@interface GlobalGem : NSObject {
 int gemTag;
}

@property int gemTag;

-(void) print;

@end

Then I created GlobalGem.m:

#import "GlobalGem.h"

@implementation GlobalGem

@synthesize gemTag;

-(void) print {
 NSLog(@"gemTag value is %i", gemTag);
}

@end

The sample code I worked from doesn't do anything I can see in "main" where the program initializes. They just have their methods and are set up to handle IBOutlet actions.

I want to use this object in the IBOutlet methods. But I don't know where to create the object.

In the viewDidLoad, I tried this:

GlobalGem *aGem = [[GlobalGem alloc]init];
[aGem print];

I added reference to the .h file of course. The print method works. In the nslog I get "gemTag value is 0".

But now I want to use the instance aGem in some of the IBOutlet actions. For instance, if I put this same method in one of the outlet actions like this:

- (IBAction)touchButton:(id)sender {

 [aGem print];

}

...I get a build error saying that "aGem is undeclared".

Yes, I'm new to objective c and am very confused.

Is the instance I created, aGem, in the viewDidLoad not accessible outside of that method?

How would I create an instance of a Class that I can store a variable value that any of the IBOutlet methods can access?

All the buttons need to be able to store their sender tag in the instance aGem and I'm stuck.

As I mentioned earlier, I was able to write the sender tag to a global variable I declared in the UIView .h file that came with the program, but I ran into issues using it.

Where am I off?

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