iOS Quick Simple Question (Passing values between classes)

[Fuzzball27]

Hello,
I would like to know how I can pass a value between two classes. For example, I would like ClassOne to get the value of the double "dVal" from ClassTwo. How can I do this?

 

[robbieduncan]

You question indicates a significant problem in your understanding of object-oriented programming. You do not pass values between classes. You pass them between objects which are instances of classes. The normal way is to define a message that allows you to do this: one instance sends a message that the second instance understands with the value or values as a parameter. One suggestion for implementation is to define a property which you can set by sending a message from the instance with the value to the instance you want to have the value.

 

[Fuzzball27]

I apologize for the lack of clarity. I will post my code to restate the question.

@interface SimonFirstViewController : UIViewController

@property (weak, nonatomic) IBOutlet UIView *firstWindow;
@property (weak, nonatomic) IBOutlet UIButton *yellowButton;
@property (weak, nonatomic) IBOutlet UIButton *orangeButton;
@property (weak, nonatomic) IBOutlet UIButton *redButton;
@property (weak, nonatomic) IBOutlet UIButton *greenButton;
@property (weak, nonatomic) IBOutlet UIButton *blueButton;
- (IBAction)yellowPressed:(id)sender;
- (IBAction)orangePressed:(id)sender;
- (IBAction)redPressed:(id)sender;
- (IBAction)greenPressed:(id)sender;
- (IBAction)centerPressed:(id)sender;
@end

This is the method that gives me an error:

- (void)dealWithBackgroundColor {
    double color = [SimonSecondViewController getColor];
    if (color == 0) {
        firstWindow.backgroundColor = [UIColor  whiteColor];
    }
    else if(color == 1) {
        firstWindow.backgroundColor = [UIColor  grayColor];
    }
    else if(color == 2) {
        firstWindow.backgroundColor = [UIColor  blackColor];
    }
}

Here is the second view class info:

@interface SimonSecondViewController : UIViewController
{
    double difficulty, color;
}

@property (weak, nonatomic) IBOutlet UIStepper *difficultyStepper;
@property (weak, nonatomic) IBOutlet UIStepper *colorStepper;
@property (weak, nonatomic) IBOutlet UISlider *SoundEffectsVolumeSlider;
@property (weak, nonatomic) IBOutlet UILabel *difficultyLabel;
@property (weak, nonatomic) IBOutlet UILabel *colorLabel;
- (IBAction)changeDifficulty:(id)sender;
- (IBAction)changeBackgroundColorInGame:(id)sender;
@end

Methods in question:

- (IBAction)changeBackgroundColorInGame:(UIStepper *)sender {
    double stepperValue = [sender value];
    NSString *colorText;
    if (stepperValue == 0) {
        colorText = @"White";
    }
    else if (stepperValue == 1) {
        colorText = @"Grey";
    }
    else if (stepperValue == 2) {
        colorText = @"Black";
    }
    self.colorLabel.text = colorText;
    color = [sender value];
}

- (double)getColor {
    return color;
}

This line "double color = [SimonSecondViewController getColor];" doesn't access the getColor method in SimonSecondViewController. How can I get the return value in the method "dealWithBackgroundColor" from "SimonFirstViewController"?

 

[ArtOfWarfare]

Class methods begin with a +, not a -, but like the previous person said, you should be accessing an instance of your class, not the class itself.

 

[dejo]

Search this forum for "sharing values" and/or "data persistence" and you'll find plenty of threads that discuss this issue and possible solutions.

 

[Fuzzball27]

Class methods begin with a +, not a -, but like the previous person said, you should be accessing an instance of your class, not the class itself.

How do I access an instance?