Programmatically change the state of a UIButton - objective-c

Question

I've got a pop-up view that loads when a user clicks on a TableView with Core Data elements. On the pop-up view I have a label that represents an int value.
The pop-up view has two butons, one for decreasing the value of the label by 1 and one for increasing it by one. So + and -
What I want to do is to disable the minus button if the label's value is 0. What I've tried is:
-(void)viewDidLayoutSubviews{
NSString *daString = currentVal.text;
NSNumberFormatter * f = [[NSNumberFormatter alloc] init];
[f setNumberStyle:NSNumberFormatterDecimalStyle];
NSNumber * myNumber = [f numberFromString:daString];
int number = [myNumber intValue];
if (number==0)
minus.enabled = NO;
else
minus.enabled = YES
}
The problem with my code is that the button stays disabled after I increase the label's value, and it's no longer equal to 0.
Any suggestions?

Answer 1

You should keep a reference to minus button e.g.
#property (strong, nonatomic) IBOutlet UIButton *minusButton;
Set it with a value of your minus button, or connect outlet in Interface Builder
in your action handler for plusButton, do something like that
-(IBAction)plusAction:(id)sender {
//Do your business logic
...
self.minusButton.enabled = YES;
}
//In your minusButton action handler
-(IBAction)minusAction:(id)sender {
//Do your business logic
...
NSString *daString = currentVal.text;
NSNumberFormatter * f = [[NSNumberFormatter alloc] init];
[f setNumberStyle:NSNumberFormatterDecimalStyle];
NSNumber * myNumber = [f numberFromString:daString];
int number = [myNumber intValue];
if (number==0)
self.minusButton.enabled = NO;
else
self.minusButton.enabled = YES
}

Answer 2

It seems like you have things the other way around. I would take a totally different approach:
Keep an instance variable (which we'll call 'count') in this viewController which holds the number. it can be an NSInteger. now add a target (self) to both buttons with a #selector(buttonPressed:). now this is how this selector should look like:
- (void)buttonPressed:(id)sender{
if (sender==plusButton)
self.count++;
if (sender==minusButton)
self.count--;
label.text = [NSString stringWithFormat:#"%d",self.count];
minusButton.enabled = (self.count>0);
}

Answer 3

I would just do this with a UIStepper, instead of the 2 buttons. You can set properties right in your storyboard/IB file that specify the max and min, increments, and a bunch of other useful things too. There are a couple video tutorials posted on YouTube that probably cover everything you'll need to know to use it.

Answer 4

Also, I have noticed one thing that...
If the button in disabled state and you are trying to change the title of normal state, it wont work.
I had to change the state to enabled and then I could manipulate title and set back to disabled.