Question: Recently I tried to simulate different GPS locations in Xcode using the GPX file option however when disconnecting my device and launching the app that simulates the location, it no longer works. Do I have to always connect it to the computer and click simulate location for it to work or can the app integrate the simulation independent of Xcode?

Answer: 
You can use derived column to do that.

In my example, the input is:

```
AccountNo
123
1234
123f
1e23

```

**Step 1: Try to cast string to integer**

Just use derived column, try to cast to I8

`(DT_I8)AccountNo`

**Step 2: Config error out, to catch error row**

The success casting rows will go to the nomarl flow, the value that can not cast to I8 will be redirect to the error flow.
The general data flow is like this (view screenshot):
[Data flow](http://i.stack.imgur.com/ffUeL.png)

To get the error value, you just drap and drop the red arrow from the driver column.

Now the red flow is contain the value that can not cast to integer
the blue flow is flow with value successful casting.

view following screenshot for detail:

[Screenshot - Step 2 Config error output](http://i.stack.imgur.com/rh3YG.png)

**Step 3: process uncast value with the way you want**

note that the output of error flow will give you 2 valuable columns are:

* [ErrorCode]
* [ErrorColumn]

Let use these column to make sure the error from "cast to integer fail".

You can refer to msdn document to lookup for `ErrorCode`.

Base on `ErrorColumn`, you can make sure the error come from column `AccountNo` or not.
Directly using conditional split you will not able to do this.

use derived column /Script component to check if data is numeric or not 

create an derived column isNumeric 

Expression : (DT\_I4)AccountNo == (DT\_I4)AccountNo ? 1 : 0

now use this in conditional split .