not able to change property of objects of NSArray - iphone

Question

I have a:
#property(nonatomic, retain) NSArray * buttonsArray;
...
...
#synthesize buttonsArray;
when the view loads I initialize it as:
buttonsArray = [[NSArray alloc] initWithObjects:
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
[UIButton buttonWithType:UIButtonTypeRoundedRect],
nil];
// this code places the buttons from buttons array on top of the images in my view. I placed those images in an array called imagesArrayV;
int counter = 0;
counter=0;
for (UIButton *button in buttonsArray) {
button = [buttonsArray objectAtIndex:counter];
[button setTag:counter]; // *********
button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[button addTarget:self action:#selector(test:) forControlEvents:UIControlEventTouchDown];
[button setTitle:#"Hello" forState:UIControlStateNormal];
UIImageView *tempImage = [imagesArrayV objectAtIndex:counter];
CGRect tempRect = tempImage.frame;
button.frame = tempRect;
[self.ViewMainV addSubview:button];
counter++;
}
the purpose of this is to save time creating all the buttons in xcode and creating the connections.
I posted a picture so that you can get an idea...
Anyways the method that get's executed when clicking a button is:
-(void) test: (id) sender{
UIButton*btn = (UIButton*)(sender);
int tagnumber = [btn tag];
NSLog(#"%i",tagnumber);
}
why is it that when I press on the buttons the tag is equal to 0 when I set it to something else ( look for : // ********* ) when creating the button. Moreover when I run this method:
-(void) someOtherMethod{
int counter = 0;
for (UIButton *button in buttonsArray) {
button = [buttonsArray objectAtIndex:counter];
button.alpha = 0;
button.titleLabel.text = #"I change the title";
counter++;
}
}
the buttons that I previously added do not change at all. also the alpha does not change. I don't know what button's I am changing when I run the last method.

Answer 1

Just below the line where you set the tag, you have the line button = [UIButton buttonWithType:UIButtonTypeRoundedRect];. This overwrites the button obviously. The action is then added to the newly created button, the buttons in the array are left unaltered.
Personally I would rewrite the code as follows:
for (int counter = 0; counter < numberOfButtons; ++counter) {
button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[button setTag:counter];
[button addTarget:self action:#selector(test:) forControlEvents:UIControlEventTouchDown];
[button setTitle:#"Hello" forState:UIControlStateNormal];
UIImageView *tempImage = [imagesArrayV objectAtIndex:counter];
CGRect tempRect = tempImage.frame;
button.frame = tempRect;
[self.ViewMainV addSubview:button];
[buttonsArray addObject:button];
}
This also avoids populating the array hardcoded, for more flexible, less error-prone code.

Answer 2

try using this code instead of the third section above:
for(int i=0;i<[buttonsArray count];i++){
UIButton *button=[buttonsArray objectAtIndex:i];
[button addTarget:self action:#selector(test:) forControlEvents:UIControlEventTouchDown];
[button setTitle:#"Hello" forState:UIControlStateNormal];
UIImageView *tempImage = [imagesArrayV objectAtIndex:counter];
button.frame = tempImage.frame;
button.tag =i;
[self.ViewMainV addSubview:button];
}
one of the issues, is that you were setting the tag on button, then replacing the button instance on the next line.

Answer 3

This looks suspicious, and you do it twice:
for (UIButton *button in buttonsArray) {
button = [buttonsArray objectAtIndex:counter];
You should not modify the loop enumeration variable button inside the loop. You simply use button as it is.
IOW, you either do:
for (counter = 0; counter < buttonsArray.count; counter++)
{
UIButton *button = [buttonsArray objectAtIndex: counter];
button.alpha = 0;
// etc...
or you simply get rid of counter and do:
for (UIButton * button in buttonsArray)
{
button.alpha = 0;
// etc...