How to save a reference to a control added programmatically? - iphone

Question

I added 3 buttons programmatically to my view, then I added the buttons to an array so that I can access them at a later time:
for (i = 0; i < 3; i++)
{
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
[view addSubview:button];
[_buttons addObject:button];
}
If I reference the button in my array and change the image of the button, it does not change the button on screen.
UIButton* button = [_buttons objectAtIndex: 0];
[button setImage:thumb forState:UIControlStateNormal];
I've found a way to change the image of the button by looping through all the subviews in my view, but is there a better way?
for (UIView* subView in ((UIView*)[self.view.subviews objectAtIndex:0]).subviews){
if ([subView isKindOfClass:[UIButton class]]){
UIButton *button = (UIButton*)subView;
if (button.tag == self.selected){
[button setImage:thumb forState:UIControlStateNormal];
}
}
}

Answer 1

A common reason for this is that your array has not been initialized. When this happens, Objective C does not complain or throw excetions: instead, it behaves as if the calls to add elements never happened. It also returns nil when you try getting items back.
Add this line to your viewDidLoad method:
_buttons = [NSMutableArray array];
This should solve the problem.

Answer 2

Possible this could help on a click event:
-(void)clickEvent:(id)sender
{
[sender setImage:thumb forState:UIControlStateNormal];
}
If this is how you are picking up the event.

Answer 3

When you do addSubview, view retains subview you are adding. Also addObject retains it. Hence both are different ojbects. Changing properties of object in array will not affect object retained by view.
You can avoid loop by using tags. While adding buttons on view set unique tags to them. And when you want to access them, get it using tag directly.
//set tags for buttons
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
[button setTag:999];
[view addSubview:button];
//access using tag
UIButton *button = (UIButton*)[view viewWithTag:999];
[button setImage:thumb forState:UIControlStateNormal];

Answer 4

Add a tag to the button after creating it. And later use that tag to get that button.
for (i = 0; i < 3; i++)
{
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
button.tag = i+1;
[view addSubview:button];
[_buttons addObject:button];
}
Then you can access it like:
UIButton *button1 = (UIButton *)[self.view viewWithTag:1];
UIButton *button2 = (UIButton *)[self.view viewWithTag:2];
UIButton *button3 = (UIButton *)[self.view viewWithTag:3];

Answer 5

While adding UIControl programatically to use reference later add tag to it which should be different like:
yourBtn.tag = 111;
Now get reference of UIButton like this:
UIButton *button = (UIButton*)[yourViewWhereYouAdded viewWithTag:111];