Reduce number in text box by one for each button tap - iphone

Question

I'm relatively new to Objective-C so this might be really simple to do: I have a text box in my application that displays an ammo count, so each time the user taps a fire button the number in the text box will go down by one (12 > 11 > 10, etc) to 0. I have tried using for and if statements, but they are not working (I may have used incorrect syntax). This is what I'm using right now, but obviously I need the
- (IBAction)fire {
[ammoField setText:#"11"];
}
- (IBAction)reload {
[ammoField setText: #"12"];
}

Answer 1

The simplest way would be to convert the text to a number, decrement that and the reset the text, i.e. replace the code in the fire method with:
NSInteger ammoCount = [ammoField.text integerValue];
ammoCount--;
ammoField.text = [NSString stringWithFormat:#"%d", ammoCount];
But don't do this, it will make baby Steve Jobs cry.
A better way would be to add a new variable to the class of type UIInteger that tracks the the number of bullets, i.e.:
// in interface
NSInteger _ammoCount;
...
// in implementation
- (IBAction)fire {
_ammoCount--;
if (_ammoCount <= 0) {
_ammoCount = 0;
fireButton.enabled = NO;
}
[ammoField setText: [NSString stringWithFormat:#"%d", _ammoCount]];
}
- (IBAction)reload {
_ammoCount = 12;
[ammoField setText: [NSString stringWithFormat:#"%d", _ammoCount]];
fireButton.enabled = YES;
}
Oh, and don't forget to call reload at some point early on to ensure _ammoCount and ammoField get initialised.

Answer 2

Set Instance Integer
int x;
set value of it
x = 12;
do change in method
- (IBAction)fire {
[ammoField setText:[NSString stringWithFormat:#"%i",x]];
x--;
}

Answer 3

set the value of count in viewdidload with an int variable
fire method decrease the count by 1
and reload method to return value to 12
log or use values accordingly

Answer 4

Try this:-
int i;
-(void)ViewDidLoad
{
i=12;
}
- (IBAction)fire
{
[ammoField setText:[NSString stringWithFormat:#"%d",i]];
i--;
}
- (IBAction)reload {
i = 12;
[ammoField setText: [NSString stringWithFormat:#"%d", i]];
}
Hope it will work for you. Thanks :)