シングルトンクラス

DataBaseManager.h
#import <Foundation/Foundation.h>
#import "EGODatabase.h"

@interface DataBaseManager : NSObject{
}
+ (DataBaseManager*)sharedInstance;
@end


DataBaseManager.m
#import "DataBaseManager.h"

@implementation DataBaseManager

+ (DataBaseManager*)sharedInstance {
    static DataBaseManager* _instance;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _instance = [[DataBaseManager alloc]initSharedInstance];
    });
    return _instance;
}

- (id)initSharedInstance {
    self = [super init];
    if (self) {
    	//初期化
    }
    return self;
}
@end


使うとき
DataBaseManager*dbm=[DataBaseManager sharedInstance];