iphone - Using a singleton to create an array accessible by multiple views

Question

It's a classic problem.

I would like to access an array of objects from anywhere within my app. I would also like to do this using a singleton. My questions are:

1. Where do I instantiate my singleton object?
2. Where do I instantiate my NSMutable array of objects?
3. How do I refer to this array from anywhere within my project?

All code and examples are greatly appreciated!

EDIT 1

This is what I have so far. I can't figure out though how to access this array of bananas correctly and consistently:

#import <Foundation/Foundation.h>

@interface Singleton : NSObject {
    NSMutableArray *bananas;
}

@property (nonatomic, retain) NSMutableArray *bananas;

@end


#import "Singleton.h"

static Singleton *mySingleton;

@implementation Singleton

@synthesize bananas;

#pragma mark SingletonDescption stuff

+ (Singleton *)mySingleton
{
    if(!mySingleton){
        mySingleton = [[Singleton alloc]init];
    }

    return mySingleton;
}

+ (id)allocWithZone:(NSZone *)zone
{
    if (!mySingleton) {
        mySingleton = [super allocWithZone:zone];
        return mySingleton;
    } else {
        return nil;
    }
}

- (id)copyWithZone:(NSZone*) zone
{
    return self;
}

- (void)release
{
    // NO OP
}

@end

EDIT 2

This is how I'm trying to use my singleton object to have an array of objects placed in a table cell. Nothing is happening and the table cell comes up blank :(

- (id)init
{
    [super initWithStyle:UITableViewStylePlain];

    // bananas = [[NSMutableArray alloc] init];

    Singleton *mySingleton = [[Singleton alloc]init];
    mySingleton.bananas = [[NSMutableArray alloc]init];

    UIImage *imageA = [UIImage imageNamed:@"A.png"];
    UIImage *imageB = [UIImage imageNamed:@"B.png"];
    UIImage *imageC = [UIImage imageNamed:@"C.png"];

    Banana *yellowBanana = [[Banana alloc] initWithName:@"Yellow" description:@"Beautiful" weight:22.0 icon:imageA];
    Banana *greenBanana =  [[Banana alloc] initWithName:@"Green" description:@"Gorgeous" weight:12.0 icon:imageB];
    Banana *rottenBanana = [[Banana alloc] initWithName:@"Rotten" description:@"Ugly" weight:8.0 icon:imageC];

    [mySingleton.bananas addObject:yellowBanana];
    [mySingleton.bananas addObject:greenBanana];
    [mySingleton.bananas addObject:rottenBanana];
}

Answer 1

Do your singleton like this:

@interface Singleton : NSObject
@property (nonatomic, retain) NSMutableArray *bananas;
+(Singleton*)singleton;
@end
@implementation Singleton
@synthesize bananas;
+(Singleton *)singleton {
    static dispatch_once_t pred;
    static Singleton *shared = nil;
    dispatch_once(&pred, ^{
        shared = [[Singleton alloc] init];
        shared.bananas = [[NSMutableArray alloc]init];
    });
    return shared;
}
@end

The singleton is initialized the first time you use it. You can call it from anywhere at any time:

NSLog(@"%@",[Singleton singleton].bananas);