+(BOOL)validateUserName:(NSString *)name
{
NSString *userNameRegex =@"^[A-Za-z0-9]{3,20}+$";
NSPredicate *userNamePredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",userNameRegex];
BOOLB = [userNamePredicate evaluateWithObject:name];
returnB;
}
