Delegate to 'Parent' ViewController best practice - objective-c

Question

The setup:
PickerView (spinSelector) and label (chosenItem) added to ViewController.
Created separate delegate class files (SpinDelegate m&h) for the PickerView delegate.
Created instance of the delegate (SpinDelegate *mySpinDelegate)
Assigned delegate property to delegate instance
ViewController.h
#interface ViewController : UIViewController
{
SpinDelegate *mySpinDelegate;
}
#property (nonatomic, weak) IBOutlet UILabel *chosenItem;
#property (nonatomic, strong) IBOutlet UIPickerView *spinSelector;
ViewController.m
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
mySpinDelegate=[[SpinDelegate alloc]init];
self.spinSelector.delegate=mySpinDelegate;
self.spinSelector.dataSource=mySpinDelegate;
}
SpinDelegate.h
#interface SpinDelegate : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate>
{
ChoiceData *choiceItems;
}
#end
SpinDelegate.m
#pragma mark - PickerView Delegate
- (NSString *)pickerView:(UIPickerView *)pickerView
titleForRow:(NSInteger)row
forComponent:(NSInteger)component{
return [choiceItems.choiceList objectAtIndex:row];
}
Next is to use the method:
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component;
This is part of the UIPickerViewDelegate protocol. Using this, to simply change the UILabel (chosenItem) in the ViewController to value of row. Something like "The picked item is %i",row
I've read and searched through a ton of posts and questions on UIViewController to UIViewController messaging and looked at protocol/delegate, singleton, NSNotificationCenter... it just seems to me that there is a syntax I am missing to address the parent/super? The ViewController created the instance of the delegate, doesn't the delegate have scope?
Please educate me on this. : )

Answer 1

You can do something like this:
ViewController.h
#import "SpinViewController.h"
#interface ViewController : UIViewController<SpinViewControllerDelegate>
{
}
#property (nonatomic, weak) IBOutlet UILabel *chosenItem;
#property (nonatomic, strong) IBOutlet UIPickerView *spinSelector;
ViewController.m
- (void)someFunction
{
mySpinViewController=[[SpinViewController alloc]init];
mySpinViewController.delegate=self;
// show or present mySpinViewController
}
//implement the followed protocol's method
-(void) optionSelected:(NSString*)cellValue{
}
SpinViewController.h
#protocol SpinViewControllerDelegate <NSObject>
#optional
-(void) optionSelected:(NSString*)cellValue;
#end
#interface SpinViewController : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate>
{
ChoiceData *choiceItems;
}
#property (nonatomic,retain)id <SpinViewControllerDelegate> delegate;
#end
SpinViewController.m
-(void) pickerValueSelectedOrSimilarFn:(NSString*)cellValue{
// this is how you give a callback to classes following the protocol
[self.delegate optionSelected:cellValue];
}