Question

I am creating (the user pressing a button) many UIImageViews programmly, and assigning a tag to each when created in this way:

    int a;

    if (a != nil){

        a = 0;
    }

    a = a + 1;
    image1.tag = a;

the problem is that with a = a +1 I would like the variable to increase: 1,2,3,4… but it remains always 1, so each Image has a tag of 1. if I add a++, the tag 2 is assigned to all. why?? Thanks for the answer

Answer 1

This is assuming a is a simple type.

Firstly you should never compare a simple type like so;

if (a != nil){
    a = 0;
}

However, the if statement above will always be true after the first button is pressed because a will be > 0 and therefore will not evaluate to NULL. So your if statement will always reset a back to zero. If you want the tag to increment remove that if statement.

Assuming a is not a simple type.

Make a an int and also remove the if statement. Heres is some supporting code.

@implementation ViewController{
    int a;
}
-(void)pressed{
    a = a + 1;
    NSLog(@"%d",a);
}
- (void)viewDidLoad{
    [super viewDidLoad];
    a = 0;
    UIButton * b = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    b.frame = CGRectMake(0, 0, 100, 50);
    [b addTarget:self action:@selector(pressed) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:b];
}
@end