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static AccountManager *DefaultManager = nil;  
 
+ (AccountManager *)defaultManager {  
    if (!DefaultManager) DefaultManager = [[self allocWithZone:NULL] init];  
    return DefaultManager;  
}

static AccountManager *DefaultManager = nil; + (AccountManager *)defaultManager { if (!DefaultManager) DefaultManager = [[self allocWithZone:NULL] init]; return DefaultManager; }

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+ (AccountManager *)sharedManager  
{  
        static AccountManager *sharedAccountManagerInstance = nil;  
        static dispatch_once_t predicate;  
        dispatch_once(&predicate, ^{  
                sharedAccountManagerInstance = [[self alloc] init];   
        });  
    return sharedAccountManagerInstance;  
}

+ (AccountManager *)sharedManager { static AccountManager *sharedAccountManagerInstance = nil; static dispatch_once_t predicate; dispatch_once(&predicate, ^{ sharedAccountManagerInstance = [[self alloc] init]; }); return sharedAccountManagerInstance; }