How to access variable across controllers?

Question

So I have this declared in my ViewController.h:

@property (nonatomic) BOOL areThereAds;

How can I access this variable in my AppDelegate.m class so that I can load a different storyboard with a different layout if areThereAds == NO.

Something like:

UIStoryboard *storyboard;

if (areThereAds == NO){
   storyboard == [UIStoryboard storyboardWithName:@"Main_iPhone-noAds" bundle:nil];
}
else{
   storyboard == [UIStoryboard storyboardWithName:@"Main_iPhone" bundle:nil]
}

Is the decision of whether or not there are ads made by the ViewController (i.e. it's a display decision) or the application delegate (..it's an application-wide issue)? — JBRWilkinson
– JBRWilkinson, Commented Aug 14, 2014 at 21:07

Subash · Accepted Answer · 2014-08-15 16:13:50Z

2

Another way to access a boolean throughout the app is to store it in [NSUserDefaults standardUserDefaults] as follows:

[[NSUserDefaults standardUserDefaults] setBool:NO forKey:@"isCompleted"];
[[NSUserDefaults standardUserDefaults] synchronize];

To retrieve it from any class

BOOL someBool = [[NSUserDefaults standardUserDefaults] boolForKey:@"isCompleted"];

edited Aug 15, 2014 at 16:13

answered Aug 14, 2014 at 20:33

Subash

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Comments

hombero · Accepted Answer · 2014-08-15 17:25:52Z

When I was working with passing data related to an external API response I created a singleton class which I could include the header of in each ViewController implementation file and then subsequently get the singleton instance and then retrieve its values.

For example:

Inside ViewController1.h:

#include "SingletonClass.h"

Inside ViewController1.m:

[[SingletonClass getClassInstance] someBool:YES];

Inside the header file of a class you want to retrieve the variable from:

#include "SingletonClass.h"

Inside the implementation file of a class you want to retrieve the variable from:

bool someBool =  [[SingletonClass getClassInstance] someBool]
if (someBool) {

} else {

}

I am not in front of my Mac at the moment so this may not be totally syntactically correct, but I hope it may give you an idea of how you could accomplish your question

Note: IMO the accepted answer's use of NSUserDefaults is bad practice as it is a system wide database of user preferences, assigning application specific values to it feels like using it for something it wasn't meant for. (Do we want a Windows-style registry usage on Mac?)

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