使用单例创建可以由多个视图访问的数组 [英] Using a singleton to create an array accessible by multiple views

问题描述

这是一个经典的问题。

我想从应用程式内任何地方存取物件阵列。我也想这样做使用单身。我的问题是：

1. 我在哪里实例化我的单例对象？


2. NSMutable对象数组？


3. 如何在项目中的任何地方引用此数组？

所有代码和示例都非常感谢！

编辑1

是我到目前为止。我不知道如何正确和一致地访问这个香蕉阵列：

  #import基础/基础。 h。 
 
 @interface Singleton：NSObject {
 NSMutableArray * bananas; 
} 
 
 @property（nonatomic，retain）NSMutableArray * bananas; 
 
 @end 
 
 
 #importSingleton.h
 
 static Singleton * mySingleton; 
 
 @implementation单例
 
 @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

是我如何使用我的单例对象有一个对象数组放置在表单元格。没有发生任何事情，表格单元格空白：（

   - （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： bp]; 
 UIImage * imageC = [UIImage imageNamed：@C.png]; 
 
 Banana * yellowBanana = [[Banana alloc] initWithName：@描述：@Beautifulweight：22.0 icon：imageA]; 
 Banana * greenBanana = [[Banana alloc] initWithName：@Greendescription：@Gorgeousweight：12.0 icon：imageB]; 
 Banana * rottenBanana = [[Banana alloc] initWithName：@Rottendescription：@Uglyweight：8.0 icon：imageC]; 
 
 [mySingleton.bananas addObject：yellowBanana]; 
 [mySingleton.bananas addObject：greenBanana]; 
 [mySingleton.bananas addObject：rottenBanana]; 
} 
  

解决方案

  @interface Singleton：NSObject 
 @property（nonatomic，retain）NSMutableArray * 
 +（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 
  

singleton在您第一次使用时。您可以随时随地调用它：

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

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];
}

解决方案

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);

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