How does this code work to create buttons? - iphone

Question

I am wondering how exactly the following piece of code works (yes, it indeed works as intended, and it gives different values of tag, depending on which button was clicked.)
The point is: Aren't we reusing button 7 times, where are the other 6 buttons left? After executing this code do we really have memory reserved for 7 UIButtons?
Or as a more general question: Is this good programming style? The point is that I need to have a different action depending on which button was clicked, and this approach (with my limited objc skills) looked like the most straightforward.
Thanks in advance,
A beginning iOS developer.
UIButton *button;
for(int k=0;k<7;k++)
{
button = [UIButton buttonWithType:UIButtonTypeCustom];
[button addTarget:self
action:#selector(aMethod:)
forControlEvents:UIControlEventTouchUpInside];
[button setTitle:#"" forState:UIControlStateNormal];
button.frame = CGRectMake(80, 20+30*k, 30, 30);
button.backgroundColor=[UIColor clearColor];
button.tag=k;
[subview addSubview:button];
}
Where the function aMethod: is defined as:
-(IBAction)aMethod:(id)sender
{
UIButton *clickedButton=(UIButton *) sender;
NSLog(#"Tag is: %d",clickedButton.tag);
}

Answer 1

No, you are not reusing the UIButton seven times: each iteration of the loop creates a new instance of UIButton in a call to the class method buttonWithType:, and assigns it to the variable of the same name:
[UIButton buttonWithType:UIButtonTypeCustom];
Your code would be better off if you declared that variable inside the loop:
for(int k=0;k<7;k++)
{
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
// ...the rest of the loop
}
This is a very good programming style for situations when your buttons perform very similar actions. For example, calculator buttons differ only in the number that they insert. When the buttons perform actions that differ a lot (e.g. insertion vs. deletion) you are better off creating them separately, not in a loop, and servicing their clicks using separate methods.

Answer 2

In this code you just create 7 buttons with different positions and tags. It is much more better, then duplicate creation code for 7 times. The one thing, that I can offer you - to create some enum for button tags to prevent code like this:
switch([button tag])
{
case 1:
// do something
break;
case 2:
// do something else
break;
case 3:
// exit
break;
.....
default:
assert(NO && #"unhandled button tag");
}
the code with enum values much more easy to read
switch([button tag])
{
case kButtonForDoSomething:
// do something
break;
case kButtonForDoSomethingElse:
// do something else
break;
case kButtonExit:
// exit
break;
.....
default:
assert(NO && #"unhandled button tag");
}

Answer 3

This code does suffice, you're creating 7 different buttons and adding them as subviews. Once you -addSubview:, the object is added to an array, Accessed via the .subviews property of UIView.
Although you should add UIButton *button in your for loop. So your code should look like below..
for(int k=0;k<7;k++)
{
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
....
}
If you needed to do something out of the for loop with the button then declaring it outside the loop makes sense, but this is not your case. Hope this helps.