How to use global variables in Objective-C?

Question

How should I declare a global variable in my Objective-C project?

Answer 1

In my experience there are few instances when a program doesn't need, at least, some sort of data or utility/helper methods that can be accessed throughout the program.

They way I deal with this, rather than using global variables is to create what I call a 'project applicance', which is essentially just a class with a bunch of static methods.

It could be implemented multiple ways, but I use a singleton and just have the static methods call through to the single instance of the appliance class. For example, in my project Oovium I have:

Oovium.h:

@interface Oovium : NSObject {
    UIWindow* _window;
}

+ (UIWindow*) window;

Oovium.m:

@implementation Oovium

static Oovium* oovium;

- (UIWindow*) window {return _window;}

+ (void) initialize {
    oovium = [[Oovium alloc] init];
}

+ (UIWindow*) window {return [oovium window];}

I then include Oovium.h in my Oovium_Prefix.pch file so that it is automatically included in all of my files.