iOS: change png in a bar button item - ios

Question

I put in a tolbar a bar button item, and I set it with a png (first.png) and when I push it I want to change its png in "second.png"
This code doesn't work fine:
UIImage *first = [UIImage imageNamed:#"first.png"];
UIImage *second = [UIImage imageNamed:#"second.png"];
if ([sender isSelected])
{
[sender setImage:first forState:UIControlStateNormal];
[sender setSelected:NO];
}
else
{
[sender setImage:second forState:UIControlStateSelected];
[sender setSelected:YES];
}

Answer 1

The current answerers do not realize that UIBarButtonItem does NOT inherit from UIButton, so setImage:forState: will most definitely not work. UIBarButtonItems cannot be set for different states. You can, however, utilize something like this (declared in the UIBarItem docs):
sender.image = [UIImage imageNamed:#"first.png"];

Answer 2

I'm not clear on why you have an if block in there. Can't you initialize both state images as a one-off initialization step? I.e.
[sender setImage:[UIImage imageNamed:#"first.png"] forState:UIControlStateNormal];
[sender setImage:[UIImage imageNamed:#"second.png"] forState:UIControlStateSelected];
In fact, this can probably be done in Interface Builder if you don't need to do it programmatically.

Answer 3

Just write after creation of button this lines:
UIImage *first = [UIImage imageNamed:#"first.png"];
UIImage *second = [UIImage imageNamed:#"second.png"];
[sender setImage:first forState:UIControlStateNormal];
[sender setImage:second forState:UIControlStateSelected];
You don't need if-else statement.
Updated:
CGRect myFrame;
UIButton *myButton = [[UIButton alloc] initWithFrame:myFrame];
[myButton setImage:[UIImage imageNamed:#"first.png"] forState:UIControlStateNormal];
[myButton setImage:[UIImage imageNamed:#"second.png"] forState:UIControlStateSelected];
UIBarButtonItem *barItem = [[UIBarButtonItem alloc] initWithCustomView:myButton];
[myButton release];