Question

Dear all.
I need to keep some temporary information in code. When i access to it, i make instant copy of my class, receive result as MutableArray, but i have to using this array in other method’s of code.
I don’t like to make instant copy of my class again, bcs this take memory and processor time, but i have to using rest of array in other methods.
Currently i keep it in array controller, but i like to find other better way.
In some reasons i don’t like to send pointer to this MutableArray as method’s parameter.
ProjectArrays.h:

#import <Cocoa/Cocoa.h>
@interface ProjectArrays : NSObject {
NSMutableArray *myMutableArray;    
}
@property (nonatomic, retain) NSMutableArray *myMutableArray;
+(ProjectArrays *)sharedProjectArrays;

@end

ProjectArrays.m:

#import "ProjectArrays.h"
#import "SynthesizeSingleton.h"

@implementation ProjectArrays

SYNTHESIZE_SINGLETON_FOR_CLASS(ProjectArrays)

@synthesize myMutableArray;

- (void)dealloc {
// Clean-up code here.
[myMutableArray release];
[super dealloc];
}

@end

AppDelegate.m:

[[ProjectArrays sharedProjectArrays].myMutableArray addObject:@"Test"];

NSLog (@"This is test first point:%@",[[ProjectArrays sharedProjectArrays].myMutableArray objectAtIndex:0]);

2010-11-21 19:26:18.636 snow[14523:a0f] This is test first point:(null)

looks like code can’t care objects.

Answer 1

Try using singleton pattern. Create some singleton class and keep there environmental variables.

Here is useful header file: http://snipplr.com/view/32737/synthesizesingleton-definition-header/

It will help you to create singletons promptly.

EDITED:

Here is a singleton you’d like to use

//YourSingletonClassName.h
#import <Foundation/Foundation.h>


@interface YourSingletonClassName : NSObject {
  NSMutableArray *myMutableArray;
}

@property (nonatomic, retain)   NSMutableArray *myMutableArray;

+ (YourSingletonClassName *)sharedYourSingletonClassName;

@end


//YourSingletonClassName.m
#import "YourSingletonClassName.h"
#import "SynthesizeSingleton.h"

@implementation YourSingletonClassName

SYNTHESIZE_SINGLETON_FOR_CLASS(YourSingletonClassName)

@synthesize myMutableArray;

- (id) init
{
  self = [super init];
  if (self != nil) {
     self.myMutableArray = [NSMutableArray new];
  }
  return self;
}


- (void) dealloc {
  [myMutableArray release];
  [super dealloc];
}

@end

You can call YourSingletonClassName anywhere by [YourSingletonClassName sharedYourSingletonClassName];, you shouldn’t alloc/init it, e.g:

[[YourSingletonClassName sharedYourSingletonClassName].myMutableArray addObject:@"some_object_to_add"];

Please google for singleton pattern and dig through obj c conceptions.