Retain Subview contents from one View Controller to another - objective-c

Question

I'm using the Cordova cleaver to insert some subview into parts of my native app. I'm having difficulty retaining the contents of these subviews between the pages of my app. For example if I go from ViewController1 to ViewController2 and then back again the contents of the subview on the first view controller has reset as if it had just been loaded for the first time. I'd like a way to preserve these subviews across the app so they don't reset as a user moves around.
Here's what I'm doing right now:
Retaining the subview as a property in ViewController.h
#import <UIKit/UIKit.h>
#import <Cordova/CDVViewController.h>
#interface ViewController : UIViewController
#property (nonatomic,retain) CDVViewController* viewController;
#end
And then loading it here like so in ViewController.m
#import "ViewController.h"
#import <Cordova/CDVViewController.h>
#interface ViewController ()
#end
#implementation ViewController
#synthesize viewController;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
viewController = [CDVViewController new];
viewController.useSplashScreen = NO;
viewController.view.frame = CGRectMake(0, 44, 320, 450);
[self.view addSubview:viewController.view];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
Any help or pointing in the right direction is greatly appreciated.

Answer 1

There are a few approaches you could take here. One of them is to use a singleton pattern for your view controller, so that only one instance is ever created. With that pattern, the view controller will retain its state because it will never be re-created. An example of that pattern for objective c is here.
But that may not be the best approach. Another option is to store the parts of your view controller that you want to keep the same as static variables, so that if a new instance of the view controller is created, the portions of your view controller that you want to preserve will still be the same. If you do that, you can restore the state of your view controller in a viewDidAppear method.
If you were to use the second approach, I would do it like this. First, remove the #property declaration from your header file for the CDVViewController. Then, in your implementation file do something like this:
#import "ViewController.h"
#import <Cordova/CDVViewController.h>
#interface ViewController ()
#end
#implementation ViewController
static CDVViewController *__MY_STATIC_CDVViewController;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
if( ! __MY_STATIC_CDVViewController ) {
__MY_STATIC_CDVViewController = [CDVViewController new];
__MY_STATIC_CDVViewController.useSplashScreen = NO;
__MY_STATIC_CDVViewController.view.frame = CGRectMake(0, 44, 320, 450);
}
[self.view addSubview: __MY_STATIC_CDVViewController.view];
}
#end
I would add that this recommendation isn't the best overall approach for your problem, but it should work for your needs.