Code-Bin #656 - SharedDBManager

SharedDBManager
Posted by: Ashok Menon | May 26, 2010 @ 12:45pm

Objective C Code

//
//  SharedDBManager.h
//  ClassVarTest
//
//  Created by Ashok Menon on 26/05/2010.
//  Copyright 2010 __MyCompanyName__. All rights reserved.
//

#import <Cocoa/Cocoa.h>

@interface SharedDBManager : NSObject {

}

-(id)init;
-(void)instanceAddsRecord:(id)obj;
-(id)instanceReturnsObjectAtIndex:(NSUInteger)index;
-(int)instanceReturnsInstanceCount;
+(void)initializeSharedDB;
+(id)returnObjectAtIndex:(NSUInteger)index;
+(int)instanceCount;
+(void)addRecord:(id)obj;
-(void)dealloc;
+(void)purgeSharedDB;
+(void)reInitializeSharedDB;

@end

//
//  SharedDBManager.m
//  ClassVarTest
//
//  Created by Ashok Menon on 26/05/2010.
//  Copyright 2010 __MyCompanyName__. All rights reserved.
//

#import "SharedDBManager.h"

static NSMutableArray *SharedDB;
static int count;

@implementation SharedDBManager

-(id)init {
	if (self = [super init]) {
		count ++;
	}
	return self;
}

-(void)instanceAddsRecord:(id)obj {
	[SharedDBManager addRecord:obj];
}

-(id)instanceReturnsObjectAtIndex:(NSUInteger)index {
	return [SharedDBManager returnObjectAtIndex:index];
}

-(int)instanceReturnsInstanceCount {
	return count;
}

+(void)initializeSharedDB{
	SharedDB = [[NSMutableArray alloc] init];
	count = 0;
}

+(id)returnObjectAtIndex:(NSUInteger)index {
	return [SharedDB objectAtIndex:index];
}

+(int)instanceCount {
	return count;
}

+(void)addRecord:(id)obj {
	[SharedDB addObject:obj];
}

-(void)dealloc {
	count--;
	[super dealloc];
}

+(void)purgeSharedDB {
	SharedDB = nil;
}

+(void)reInitializeSharedDB {
	[SharedDBManager purgeSharedDB];
	SharedDB = [[NSMutableArray alloc] init];
}

@end

//
//  ClassOne.h
//  ClassVarTest
//
//  Created by Ashok Menon on 26/05/2010.
//  Copyright 2010 __MyCompanyName__. All rights reserved.
//

#import <Cocoa/Cocoa.h>

@class SharedDBManager;

@interface ClassOne : NSObject {
	SharedDBManager *dbManager;
}

@property (nonatomic, retain) SharedDBManager *dbManager;

-(id)init;
-(void)dealloc;

@end

//
//  ClassOne.m
//  ClassVarTest
//
//  Created by Ashok Menon on 26/05/2010.
//  Copyright 2010 __MyCompanyName__. All rights reserved.
//

#import "ClassOne.h"
#import "SharedDBManager.h"

@implementation ClassOne

@synthesize dbManager;

-(id)init {
	if (self = [super init]) {
		dbManager = [[SharedDBManager alloc] init];
		
		NSString *record = [NSString 
							stringWithFormat:@"Added from ClassOne"];
		[dbManager instanceAddsRecord:record];
		[record release];
	}
	
	return self;
}

-(void)dealloc {
	[dbManager release];
	[super dealloc];
}
@end

//
//  ClassOne.h
//  ClassVarTest
//
//  Created by Ashok Menon on 26/05/2010.
//  Copyright 2010 __MyCompanyName__. All rights reserved.
//

#import <Cocoa/Cocoa.h>

@class SharedDBManager;

@interface ClassTwo : NSObject {
	SharedDBManager *dbManager;
}

@property (nonatomic, retain) SharedDBManager *dbManager;

-(id)init;
-(void)dealloc;

@end

//
//  ClassOne.m
//  ClassVarTest
//
//  Created by Ashok Menon on 26/05/2010.
//  Copyright 2010 __MyCompanyName__. All rights reserved.
//

#import "ClassTwo.h"
#import "SharedDBManager.h"

@implementation ClassTwo

@synthesize dbManager;

-(id)init {
	if (self = [super init]) {
		dbManager = [[SharedDBManager alloc] init];
		
		NSString *record = [NSString 
							stringWithFormat:@"Added from ClassTwo"];
		[dbManager instanceAddsRecord:record];
		[record release];
	}
	
	return self;
}

-(void)dealloc {
	[dbManager release];
	[super dealloc];
}
@end

#import <Foundation/Foundation.h>
#import "SharedDBManager.h"
#import "ClassOne.h"
#import "ClassTwo.h"

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

[SharedDBManager initializeSharedDB];
	
	ClassOne *classA = [[ClassOne alloc] init];
	ClassTwo *classB = [[ClassTwo alloc] init];
	
	NSLog(@"Instances of SharedDB: %d", [SharedDBManager instanceCount]);
	
	NSLog(@"Object Created by ClassOne, Accessed by ClassOne: %@", [classA.dbManager instanceReturnsObjectAtIndex:0]);
	NSLog(@"Object Created by ClassTwo, Accessed by ClassTwo: %@", [classB.dbManager instanceReturnsObjectAtIndex:1]);
	NSLog(@"Object Created by ClassOne, Accessed by Class Two: %@", [classB.dbManager instanceReturnsObjectAtIndex:0]);
	NSLog(@"Object Created by ClassTwo, Accessed by Class One: %@", [classA.dbManager instanceReturnsObjectAtIndex:1]);
    NSLog(@"Object Created by ClassOne, Accessed by SharedDBManager: %@", [SharedDBManager returnObjectAtIndex:0]);
	NSLog(@"Object Created by ClassTwo, Accessed by SharedDBManager: %@", [SharedDBManager returnObjectAtIndex:1]);
	
	[SharedDBManager reInitializeSharedDB];
	
	[SharedDBManager addRecord:@"First Record, Created by SharedDBManager"];
	
	NSLog(@"Object Created by SharedDBManager, Accessed by Class One: %@", [classA.dbManager instanceReturnsObjectAtIndex:0]);
	
	[classA release];
	[classB release];
	NSLog(@"Instance Count: %d", [SharedDBManager instanceCount]);
	[pool drain];
    return 0;
}

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