// 利用正则表达式验证 -( BOOL )isValidateEmail:( NSString  *)email  {  NSString  *emailRegex =  @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}" ;  NSPredicate  *emailTest = [ NSPredicate   predicateWithFormat : @"SELF MATCHES%@" ,emailRegex];  return  [emailTest  evaluateWithObject :email];  }