Question

I have 2 classes. 1st one is Label, another one is LabelGestureRecognizer. In the LabelGestureRecognizer have a method called getName, and i want call the method through the Label class.

Below is a simple example of my problem.
I am trying to call the method ‘getName’, but I am getting an error saying:
“No visible @interface for ‘LabelGestureRecognizer’ declares the selector ‘getName:’”

ViewController.h:

@property (nonatomic, strong) UILabel *valueLabel;

ViewController.m:

- (void)viewDidLoad
{
    valueLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 366, 320, 50)];
    valueLabel.textAlignment = UITextAlignmentCenter;
    valueLabel.backgroundColor = [UIColor lightGrayColor];
    [self.view addSubview:valueLabel]; 
}

- (void) wheelDidChangeValue:(NSString *) newValue {
    self.valueLabel.text = newValue;
}

Label.h:

@protocol LabelDelegate <NSObject> 
@required
 -(void) wheelDidChangeValue:(NSString *) newValue;
@end

@class LabelGestureRecognizer;

LabelGestureRecognizer.m:

- (NSString *) getName:(int) position
{
    NSString *resultat = @"";
    switch (position) {
        case 0:
            resultat = @"Test 1";
            break;
        case 1:
            resultat = @"Test 2";
            break;
        default:
            break;
    }
    return resultat;
}

LabelGestureRecognizer.h:

 @interface LabelGestureRecognizer : UIGestureRecognizer
 {
     NSDate *previous;
     double current;
 }

Label.m:

 LabelGestureRecognizer *recognizer = [[LabelGestureRecognizer alloc] init];
 [self.delegate wheelDidChangeValue:[self getName:0]];

Answer 1

When you are using self in Label.m, that represents the current class object. If you need to represent LabelGestureRecognizer object, you need to use that in place of self as,

[self.delegate wheelDidChangeValue:[recognizer getName:0]];

Also you should declare the following in your LabelGestureRecognizer.h file as,

@interface LabelGestureRecognizer : UIGestureRecognizer
 {
     NSDate *previous;
     double current;
 }
- (NSString *) getName:(int) position;
@end

Your error message is saying that it is not able to see the declaration of getName method in LabelGestureRecognizer.h class file.