Method dont change the value of variable - ios

Question

First, sorry for this question, but I am new on iOS development, and i am stuck on this all afternoon, I'm trying to change the value of a int variable using one slider located in a another viewController.
The slider of the row is located in a modal window inside the view, i think that this is the problem, but i don't know.
This is the code:
#interface ViewController ()
#property int row, column, actualGame;
#end
- (IBAction)rowChanged:(id)sender {
UISlider *slider = (UISlider *)sender;
int val = slider.value;
[self setRow: val];
self.rowLabel.text = [NSString stringWithFormat:#"%d",val];
}
- (IBAction)columnChanged:(id)sender {
UISlider *slider = (UISlider *)sender;
int val = slider.value;
_column = val;
self.collumLabel.text = [NSString stringWithFormat:#"%d",val];
}

Answer 1

In order to pass data between view controllers, there are a couple of different options available to you. The simplest would be to just store a reference to the first view controller on your second view controller. You can set the property in the `prepareForSegue' method of your first view controller.
FirstViewController.h (the view controller that's presenting the modal VC):
#import <UIKit/UIKit.h>
#interface FirstViewController : UIViewController
#property (nonatomic) float sliderValue;
#end
FirstViewController.m
#import "FirstViewController.h"
#import "ViewController.h"
#implementation FirstViewController
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:#"mySegueDefinedInStoryboard"]) {
ViewController *destinationViewController = (ViewController *)segue.destinationViewController;
destinationViewController.firstViewController = self;
}
}
#end
ViewController.h (the modal view controller):
#import <UIKit/UIKit.h>
#class FirstViewController;
#interface ViewController : UITableViewController
#property (nonatomic, weak) FirstViewController *firstViewController;
#end
ViewController.m
#import "ViewController.h"
#import "FirstViewController.h"
#implementation ViewController
- (IBAction)columnChanged:(UISlider *)sender {
float value = sender.value;
self.firstViewController.sliderValue = value;
}
#end
The downside of this method is that it creates tightly coupled code - ViewController needs to know about FirstViewController, which isn't optimal. Once you get a little bit more practiced, you'll learn about creating your own delegate, so that you can send messages to other view controllers without caring what their class is or what their properties are.
Apple Documentation on the Delegate Pattern