Windows Phone 7 : FileStream exception - exception

Question

I try to use FileStream (using namespace System.IO) but I get an exception :
Attempt to access the method failed
Here is the code :
FileStream fs = new FileStream("file.txt", FileMode.Create);
I searched on microsoft.com and I found that this error is because I use a bad library reference.
But in my project, I compile with mscorlib.dll from folder : C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\Silverlight\v4.0
I need some help, please.

Answer 1

You will need to use IsolatedStorage, for example:
Place at the top of your file:
using System.IO.IsolatedStorage;
Then in your method do this:
using (var store = IsolatedStorageFile.GetUserStoreForApplication())
{
using (var istream = new IsolatedStorageFileStream("File.txt", FileMode.OpenOrCreate, store))
{
using (var sw = new StreamWriter(istream))
{
sw.Write("Some Stuff");
}
}
}
A great example and explanation of this and other operations can be found here: http://msdn.microsoft.com/en-us/library/cc265154(v=VS.95).aspx#Y300
You can look through your IsolatedStorage by using the Windows Phone 7 IsolatedStorageExplorer
A good place to start for documentation: http://msdn.microsoft.com/library/ff626516(v=VS.92).aspx
Also here: http://create.msdn.com/en-us/education/documentation

Answer 2

On WindowsPhone you must use IsolatedStorage - see this tutorial for example - http://3water.wordpress.com/2010/08/07/isolated-storage-on-wp7-ii/
Read:
using (var store = IsolatedStorageFile.GetUserStoreForApplication())
using (var readStream = new IsolatedStorageFileStream(fileName, FileMode.Open, store))
using (var reader = new StreamReader(readStream))
{
return reader.ReadToEnd();
}
Write:
using (var store = IsolatedStorageFile.GetUserStoreForApplication())
using (var writeStream = new IsolatedStorageFileStream(fileName, FileMode.Create, store))
using (var writer = new StreamWriter(writeStream))
{
writer.Write(content);
}