How would I create and write to a file in a Monotouch iPhone app?
The file should persist between application launches, so I guess it has to be placed somewhere in the App bundle ( documents or resources?).
[Note: My response is pretty thorough because I don't know your level of understanding regarding app bundles or the structure of your iPhone app's sandboxed little world - apologies if I cover things you already know - I prefer to write a little too much than too little, and to add a bit of the why when discussing the how...]
You have a few options (of course). I'm assuming you're already familiar with .Net to some extent and that your question is more about how to do this the iPhone Way.
Every iPhone app (and you'll see the same thing for apps on OS X) is a "bundle" which isn't an executable in the traditional sense, but actually a folder hierarchy inside of which your app binary lives (along with resources, settings, etc.).
Because of how uber-sandboxed iPhone apps are, you don't have access to the shared folders you'd usually be able to use when doing desktop development (having, for example, a common Documents folder that lives under a user's home folder to which applications have access).
Instead, your app has its own folder hierarchy that's like its own personal set of the folders that would typically be shared across apps.
The easiest way to see what your app's folder structure looks like on the phone is to look at the folder the iPhone simulator uses for app installs, settings, blah blah blah. On my machine (I don't recall if this is configurable, but it's probably the same on your system), you can get to the folder by this path:
~/Library/Application Support/iPhone Simulator
Inside of that, there's a User/Applications folder that contains the apps you've installed to the simulator. Drill down into any one of those folders, and you can see the folder structure your app will have access to on the phone.
For storing files that you'd like persisted across app sessions, your app's Documents folder is the spot. It's not your only choice for creating files, but it's the right choice for this job. In addition to your files being properly stored, keeping them in the Documents folder will also get them backed up by iTunes when the user syncs.
With MonoTouch, you can get your app's Documents folder path with Environment.GetFolderPath(Environment.SpecialFolder.Personal);
If you'd like to test it out, this is some extremely simple code that'll write a file called "out.txt" to your app's Documents folder. This code also reads the contents of the file to show it was created - for further verification, go to the simulator's Applications folder, sort the app folders by the date they were modified, drill down into the most recently modified, and look inside its Documents folder - you'll find "out.txt" (you can't find your app's folder by name because, when your app is installed, it gets stuffed inside a folder with a name like "2B3CA854-FADB-4DDC-9732-0E61B3DD8D8C" - sorting the folders by the date they were modified will point you to the most recently modified app, which, in this case, is whatever app contains the following code):
// For this to function, don't forget "using System.IO;"
// If you're just playing around with this to see it work, place it inside
// your AppDelegate's "FinishedLaunching" method in main.cs
string path = Environment.GetFolderPath (Environment.SpecialFolder.Personal);
string filePath = Path.Combine(path, "out.txt");
// File.WriteAllText will create a file and then write text to it. If the
// file already exists, File.WriteAllText will overwrite it.
File.WriteAllText(filePath, "Howdy, world.");
// Now we prove it worked by reading the contents of the file and then
// printing them to the console...
string text = File.ReadAllText(filePath);
Console.WriteLine(text);
So, the only thing here that's really iPhone-specific is knowing that "Environment.SpecialFolder.Personal" maps to your app's Documents folder. Beyond that, it's .Net as usual.
And, again, this was probably overkill, but I wanted to answer sufficiently thoroughly for everybody who sees it.
The following How To from the Xamarin.iOS guide site has a few pointers to where to store your files:
http://docs.xamarin.com/guides/ios/application_fundamentals/working_with_the_file_system/
You can do something like this at runtime:
using (StreamWriter writer = new StreamWriter (Path.Combine (Environment.SpecialFolders.Documents, "yourfilename.ext"))) { }
and that will create the file. To open it for reading, use the same Path.Combine() but with StreamReader.
Related
File.Exists(filePath); works perfectly inside a console application, but when I do the same thing inside uwp it doesn't detect a file.
I have tried to put breakpoints on various methods and stepped into anything that could give me some information about the issue, but I'm getting no information at all no matter what i try.
Code from UWP app:
string path = #"C:\Users\Name\Desktop\image.jpg";
if (File.Exists(path))
{
ProcessFile(path);
}
else if (Directory.Exists(path))
{
ProcessDirectory(path);
}
UWP:
When it hits File.Exists i get a return value of false, and yes i know for a fact the image is where it is.
Console:
When it hits File.Exists i get a return value of true, then goes onto the called method without any issues.
I'm expecting my code to find a File and pass the filePath into my method called "processFile".
Does UWP applications not have access to files outside of its LocalStorage or is it another issue that I'm not seeing?
UWP does not have direct access to files outside of the application folder and application data folder. That are the only two locations accessible via the System.IO APIs.
You can use StorageFile APIs to access more locations if you enable appropriate capabilities - like access to libraries or broadFileSystemAccess or use file/folder pickers. In particular, broadFileSystemAccess allows you to access the whole file system, but your app should have a good reason to do so (otherwise it will not pass the Microsoft Store certification process).
For more info see the Docs.
This is correct. UWP apps are sandboxed and cannot access files outside of LocalStorage in this way.
If you want to open a file on the users file system you have to use FileOpenPicker.PickSingleFileAsync or similar to prompt the user to pick a file, which you'll then be able to work with.
Further reading: Working with Files in UWP applications
I have a WPF program which deals with images on a canvas.
I am at the stage where I am trying to use serialization to be able to save the contents of my program and reload it at a later stage.
So At the moment when I am inserting any images into a control I am using absolute path values, I understand that this would be a bad idea for a program where I am wanting to save the state of the program and reload it at a later time.
So what is the best course of action to take in this situation.
Do I create a folder inside my WPF project for example called Images and then do I copy all Images I use in my program to this folder and then point the path to this?
Or am I completely on the wrong lines here?
If you are serializing the state data of your application, you would usually create a folder in one or more of the so-called system special folders, which you can get by a call to Environment.GetFolderPath.
You may for example store data with application scope (same for all users) in a folder below the special folder specified by the SpecialFolder.CommonApplicationData enum (which is C:\ProgramData on Windows 7 systems).
Data that is specific for the current roaming user (who works on multiple computers on a network), would be stored in a folder below SpecialFolder.ApplicationData. There is also SpecialFolder.LocalApplicationData for the non-roaming user.
You may take a look at the Environment.SpecialFolder enumeration to get an overview.
From my own experience, create a folder and save the images there. It will just make your life easier in the long run, and it makes it easy to see where the resources of the application are.
I would like to know how Windows generate folder, where will be ClickOnce application installed.
In Startmenu is "shortcut" to file, what is putted in some "startrek" folder like:
C:\Users\USERNAME\AppData\Local\Apps\2.0\GT??4KXX.PRJ\EGV???1G.??C\prin..tion_7???5a2?????74b6_0000.0002_1dae????89111c35
What does those folder names mean?
For example:
If i will have for example some settings.txt file where i want that user can change some parameters of the application. Is there way how to know, WHERE it will be installed and WHERE the file is? (Where user will find this settings.txt file).
I know that i can create the file for example in C:\ and after start the application i will modify the file in "strong" path. But i dont really like too much files, folders, whatever in C:\ and i prefer to have settings files in same folder like the application. But with ClickOnce installations is it really hard - impossible - to find that file.
It seems like when the "startrek" is something like hash of the project.
So i would like to know what does the folder means and if its some hash of the project or what is that.
To find the folder that contains your executable, you can use the Assembly.Location property.
For example:
string exeFolder = System.Reflection.Assembly.GetExecutingAssembly().Location;
However, if you want to store settings for your ClickOnce app, you shouldn't do it by writing a file to the .exe's folder.
Instead, you should use Microsoft's Application Settings support. Doing it any other way is going to be a lot of extra hassle, and Microsoft's support is very good. It does need half an hour to read through the documentation, but it's far and away the best thing to do, IMHO.
(I'm assuming that you only need the settings to be stored on the local PC for the same user to use later. If you want the settings to follow the user around (i.e. roaming settings), you can't use the Microsoft support.)
If you have more complex settings that you want to store in a file that you create directly, you should consider using the isolated storage that the answer from JRoughan mentions.
From inside the ClickOnce app you can find the default directory where files are stored using
ApplicationDeployment.CurrentDeployment.DataDirectory
Or you can use isolated storage and choose whether you want to save per application or per user.
I don't think it's possible to determine these folders from outside the app itself. If you need a known location you'll have to hard-code it.
Update
I also don't believe it's possible to infer what the install directory will be for an app. It would be unwise to use even if possible as updates to the app will not be in the same location.
If you have data that the user is modifying through your program, you will be happier if you don't leave it in the ClickOnce program directory. You can get completely messed up when there's an update. Check out this article about what to do with your data to keep it safe and be able to find it. It talks about putting it in LocalApplicationData, but if you want your user to be able to find it and edit it, just put it in MyDocuments/yourappname/settings or something like that.
I wouldn't use Isolated Storage; there are reported problems with that and ClickOnce.
So I have been writing to
Environment.SpecialFolder.ApplicationData
this data file, that upon uninstall needs to be deleted. I am using Innos Setup to build my installer. It works great for me. So my data file hangs out in the above path and I do that cause when I used to try to write it to
Application.ExecutablePath
certain boxes I tested it on would throw a nasty error at me trying to write data there. I do research and somehow its not always writable and its how i came up with the Environment.SpecialFolder.ApplicationData
That is why my data file now resides in the SpecialFolder.ApplicationData. Trouble is if the user uninstalls and reinstalls I need that file gone. It might be a short coming of my knowledge of Innos but I cannot figure out how to know where that file will be to tell innos that.
So then I thought I had a clever solution: Innos can run a file when its done uninstalling, so I had my program create this file "uninstallData.bat" that says:
del "the file in my special folder application data path"
and I wrote it out to drumroll
Application.ExecutablePath
(yes it was a while in development and I had forgot it was't doable.)
So of course I am back to square one, I need to write a file to a path Innos knows about {app} and I need it to be able to delete my data file in the SpecialFolder... i don't care how I do it i just need that file gone.
Are there other Environment. or Application. approches I have missed? Maybe somewhere that is viewable by an uninstaller AND can be written to?
As an aside, I am not sure why my box I develop on can write to the application folder no issue, but it cannot on other boxes... weird.
Any input would be great sorta lost as to how to crack this nut.
The environment location is in the user profile. If there are multiple users on the machine, and they all run the application then a copy of the file will be in each profile.
The path also depends on the OS.
Regardless, the current user's app data location is pointed to by %APPDATA% and %LOCALAPPDATA%. These Windows environment variables should be available within Innos.
Appliccation.ExecutablePath is not writable per standard defintions - the program files folder should never be manipulated by running applications. Ther area number of special folders for that. Nice that you finally found.... what is properly documented by Microsoft for a LONG time now (minimum 10 years).
I suggest you get a proper installer - WIX comes to my mind. Your problem is totally unrelated to C# - it seems to be totally a "crappy installer" issue. Or provide a PROGRAM (not bat file) to run at uninstall. What exatly is your problem there?
I need to store log files and configuration files for my application. Where is the best place to store them?
Right now, I'm just using the current directory, which ends up putting them in the Program Files directory where my program lives.
The log files will probably be accessed by the user somewhat regularly, so %APPDATA% seems a little hard to get to.
Is a directory under %USERPROFILE%\My Documents the best? It needs to work for all versions of Windows, from 2000 forward.
If you're not using ConfigurationManager to manage your application and user settings, you should be. The configuration toolkit in the .NET Framework is remarkably well thought out, and the Visual Studio tools that interoperate with it are too.
The default behavior of ConfigurationManager puts both invariant (application) and modifiable (user) settings in the right places: the application settings go in the application folder, and the user settings go in System.Environment.SpecialFolder.LocalApplicationData. It works properly under all versions of Windows that support .NET.
As for log files, System.Environment.SpecialFolder.LocalApplicationData is generally the place that you want to put them, because it's guaranteed to be user-writeable.
There are certainly cases where you wouldn't - for instance, if you want to write files to a network share so that you easily can access them remotely. There's a pretty wide range of ways to implement that, but most of them start with creating an application setting that contains the path to the shared folder. All of them involve administration.
I have a couple of complaints about ConfigurationManager and the VS tools: there needs to be better high-level documentation than there is, and better documentation of the VS-generated Settings class. The mechanism by which the app.config file turns into the application configuration file in the target build directory is opaque (and the source of one of the most frequently asked questions of all: "what happened to my connection string?"). And if there's a way of creating settings that don't have default values, I haven't found it.
Note: You can get the path to the LocalApplicationData folder in .NET by using the following function:
string strPath=System.Environment.GetFolderPath(System.Environment.SpecialFolder.LocalApplicationData);
For application settings - use System.Environment.SpecialFolder.ApplicationData - this is where a roaming profile data is stored, so it allows your user to log and work from different machines in the domain.
For log files - System.Environment.SpecialFolder.LocalApplicationData
The accepted answer notes that for log files the following is a good spot.
System.Environment.SpecialFolder.LocalApplicationData This equates to a path of C:\Users\[User]\AppData\Roaming which you can see is user specific. Like the accepted answer mentions this is a guaranteed user-writeable location and can be useful for certain situations
However in a web application environment you may be running your application under a network account and you or a coworker may need to try and track down where exactly those logs are going per application. I personally like to use the non user specific location enumeration of
System.Environment.SpecialFolder.CommonApplicationData which equates to C:\ProgramData. Yes, you will need to specify access rights for any folders you create, but it's usually a one time deal and then all of your application logs can live in one happy location.
Additionally, while looking around the Internet, there is a project out there to programatically set write access to folders you create within CommonApplicationData, Allow write/modify access to CommonApplicationData.
To be honest %appdata% is still the best place to place your config files and log files, as it serves the purpose of a placeholder to store your application data. It should not be that hard to access, just write %appdata% in explorer and you will be directed straight to your %appdata% directory.
Do not store config files in the application folder, Microsoft has stated this is NOT the ideal location. Windows has been moving towards blocking writing to C:\Program Files\ and you'll find in Vista any application that tries to write here, will fire up a UAC warning.
Windows 7 will allow users to customize what UAC popups they use (expect some power users to block most of them) and your app will fail/freeze if the user never approves this write attempt.
If you use the proper userprofile and appdata variables, then Win 2000, XP, Vista, and Win7 will map the data to the proper write friendly folder, with no UAC popups.
You can use SHGetSpecialFolderPath:
int MAX_PATH = 255;
CString m_strMyPath;
SHGetSpecialFolderPath(NULL, m_strMyPath.GetBuffer(MAX_PATH), CSIDL_COMMON_APPDATA, TRUE);
This will specify the 'special folder path' which you can safely write logs to for windows:
For XP: C:\Documents and Settings\All Users\Application Data
For Vista: C:\ProgramData
Check the MSDN page here: http://msdn.microsoft.com/en-us/library/bb762204(VS.85).aspx
The best answer depends on the nature of the logs and configurations. If they are program-wide, and don't need to survive uninstallation of the application, then I think they're fine where they are. If the logs and configurations are user specific, or need to survive uninstallation, then they belong somewhere under %USERPROFILE% - %APPDATA% being the 'proper' base directory for this type of thing.
I use the Isolation Storage for configuration. You can also use the Temp folder to store temporary information like log.