UIView reference returns NULL pointed ARC enabled - objective-c

Question

I have ARC enabled so I am unsure as to why my reference is null.
My view controller instantiates a UIView ‘theGrid’ as soon as the view is loaded.
Later I have switch inside another class (MyOtherClass) that calls the UIViewContoller - (void) updateTheGrid:(id)sender method, that method is called as per the NSLog, but when I output the UIView to see if it is there, its returns null.
What am I doing wrong? It was my impression that ARC keeps up with everything. I feel like my trouble is coming from mm "MyOtherClass" when I ViewController * vc = [[ViewController alloc] init]; because I feel like that is just creating a new instance. But if that is the case, how am i suppose to reference the old instance and call the method?
NSLOG OUTPUT
[28853:c07] Intial Grid: <GridView: 0x8e423b0; frame = (0 0; 768 1024); layer = <CALayer: 0x8e43780>>
[28853:c07] Update The Grid (null)
GridView.h
#import <UIKit/UIKit.h>
#interface GridView : UIView
- (void) gridUpdated;
#end
GridView.m
#import "GridView.h"
#implementation GridView
- (id)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if (self) {
// Initialization code
NSLog(#"initWithFrame");
}
return self;
}
- (void)drawRect:(CGRect)rect{
NSLog(#"Grid Draw Rect");
}
- (void) gridUpdated {
NSLog(#"GRID VIEW.m : Grid update called");
[self setNeedsDisplay];
}
#end
ViewController.h
#import <UIKit/UIKit.h>
#import "GridView.h"
#interface ViewController : UIViewController {
GridView *theGrid;
}
#property (strong, retain) GridView * theGrid;
- (void) updateTheGrid : (id) sender;
#end
ViewController.m
#import "ViewController.h"
#import "GridView.h"
#interface ViewController () {}
#end
#implementation ViewController
#synthesize theGrid;
- (void)viewDidLoad {
[super viewDidLoad];
//draw the grid
theGrid = [[GridView alloc] initWithFrame:self.view.frame];
NSLog(#"Intial Grid: %#", theGrid);
[self.view addSubview:theGrid];
}
- (void) updateTheGrid : (id) sender{
NSLog(#"Update The Grid %#", theGrid);
[theGrid gridUpdated];
}
#end
MyOtherClass.m
- (void) mySwitch : (id) sender {
ViewController * vc = [[ViewController alloc] init];
[vc updateTheGrid:sender];
}

Answer 1

Do not allocate ViewController object again in your MyOtherClass.m because it will create an new instance of ViewController and your previous objects which holds ViewController wil get disposed including theGrid.
So please declare a weak property of ViewController inside the MyOtherClass.m and assign it while allocating MyOtherClass.m
Example:
ViewController class
moc = [[MyOtherClass alloc] initWithFrame:self.view.frame];
moc.vc = self;
MyOtherClass.h
#property(nonatomic,weak) ViewController *vc;
MyOtherClass.m
- (void) mySwitch : (id) sender {
[self.vc updateTheGrid:sender];
}
Note:Take care about the forward declarations :)