Change integer value

[loddy1234]

This is probably a really stupid question but :
I am making an app and I need to change the value of an integer by +1 every time the button is pressed. When I define the integer, do I need to do anything different than I would when declaring an integer that's value doesn't change? Also, what code would I use to add 1 to the integer each time the button is pressed?
Example code appreciated as I am new to objective C
Thanks in advance

[thomashw]

NSInteger temp = 0;

And:

temp++;

[loddy1234]

Originally Posted by thomashw

NSInteger temp = 0;

And:

NSInteger++;

Thanks for the speedy reply

[SoulRed12]

Originally Posted by thomashw

NSInteger temp = 0;

And:

NSInteger++;

Whoa whoa whoa--huh? NSInteger++ doesn't make any sense. ++ IS the increment operator, but it can't be used after NSInteger because NSInteger is a variable type. It'd have to be something more like:

NSInteger temp;
temp++;

I prefer to use the normal "int" variable type, but to each his own, I guess.

And for your other question--no, you don't have to declare it in any different way than a variable that doesn't change. There are things called constants which can't change, ever--but declaring those is generally much different than just declaring a normal variable.

I'd look at some beginner's resources, starting, actually, with C--as Objective C is just a strict superset (that is, Objective C is like C plus other stuff). So you might consider picking up a cheap book on basic C, it will probably help you a lot.

[thomashw]

Originally Posted by SoulRed12

Whoa whoa whoa--huh? NSInteger++ doesn't make any sense.

Woops, I was sleepy. Obviously temp++.

[loddy1234]

I tried it using this code
-(IBAction) greenUp: (id) sender{
NSInteger greenValue = 0;
greenValue ++;
green.text = [NSString stringWithFormat:@"%d", greenValue];

}

green is a UITextField

now it just changes the text in the box to 1 and when the button is pressed again, it stays as 1?
any ideas why?

[Not_Appy_At_All]

Originally Posted by loddy1234

I tried it using this code
-(IBAction) greenUp: (id) sender{
NSInteger greenValue = 0;
greenValue ++;
green.text = [NSString stringWithFormat:@"%d", greenValue];

}

green is a UITextField

now it just changes the text in the box to 1 and when the button is pressed again, it stays as 1?
any ideas why?

You keep resetting it to ZERO and then incrementing it by ONE....that's why it only shows ONE.

Place the equals to ZERO outside the IBAction or...use an IF statement to handle it correctly.

[Duncan C]

Originally Posted by loddy1234

I tried it using this code
-(IBAction) greenUp: (id) sender{
NSInteger greenValue = 0;
greenValue ++;
green.text = [NSString stringWithFormat:@"%d", greenValue];

}

green is a UITextField

now it just changes the text in the box to 1 and when the button is pressed again, it stays as 1?
any ideas why?

You need to make greenValue an instance variable. Assign it a value of zero in your object's init method, and then increment it in your IBAction. Something like this:


In your .h file



@interface My_class : NSObject
{
//Delcare instance variables here
NSInteger greenValue;
}

//declare public methods here
@end


In your .m file:

@implementation My_class

- (void) doSetup;
{
  //set initial value of greenValue
  greenValue = 0;
}

- (id) init;
{
  self = [super init];
  if (!self) return nil;
  [self doSetup];
}

- (id) initWithCoder:(NSCoder *)aDecoder;
{
  self = [super initWithCoder: aDecoder]
  if (!self) return nil;
  [self doSetup];
  return self;
}

@end

Note that for objects that are created from a nib file, init does not get called. The system creates those objects with the method initWithCoder instead. Thus, I usually put my setup code in a separate method doSetup, and call that method from both init and initWithCoder. That way, the same setup gets done if you create the objects in IB or with alloc/init.