File::copyFileTo fails on iOS

MacOSX and iOS
1

I’m trying to debug an issue on iOS where a call to file.copyFileTo(newFile) fails.

jassert(newFile.hasWriteAccess()); passes.

The copyFile method:

bool File::copyFileTo (const File& newFile) const
{
    return (*this == newFile)
            || (exists() && newFile.deleteFile() && copyInternal (newFile));
}

I have confirmed that *this != newFile
The file does not exist.
deleteFile returns true.

The debugger does not take me into copyInternal at all (I have a breakpoint set there).

Any clues?

1 Like
2

I run into the same iOS problem. It works fine on MacOS.

Does anyone have any new information?

3

From where you’re trying to copy? are you using native FileChooser?
If you’re trying to copy a file outside of your app (eg from iCloud/Local Device/Files) you need to use Url and maybe even handle input/output streams yourself.

4

Yes, I’m using the native FileChooser.

void FileManager::openFileChooser(
                                  const juce::String& dialogBoxTitle,
                                  const juce::File& initialFileOrDirectory,
                                  const juce::String& filePatternsAllowed,
                                  bool useOSNativeDialogBox,
                                  bool treatFilePackagesAsDirectories,
                                  Component* parentComponent,
                                  int FileChooserFlags)
{
    fileChooser.reset (new juce::FileChooser (dialogBoxTitle, initialFileOrDirectory, filePatternsAllowed, useOSNativeDialogBox));

    fileChooser->launchAsync (juce::FileBrowserComponent::openMode | juce::FileBrowserComponent::canSelectFiles,
                     [this] (const juce::FileChooser& chooser)
                     {
                        compoListeners.call([this](Listener &l)
                        {
                            l.fileChanged(this->fileChooser->getURLResult());
                        });
                     });
    
}

And here is the copy function:


void AppSoundControls::fileChanged (juce::URL url)
{
    juce::File selectedFile = url.getLocalFile();
    if(!selectedFile.exists())
    {
        DBG(__FUNCTION__ << " - No file selected " << selectedFile.getFullPathName());
        return;
    }
    DBG(__FUNCTION__ << " - Selected file exists: " << selectedFile.getFullPathName());
    
    const juce::File newFile = FileHelpers::getProjectsDir().getChildFile(processor.getProjectState().getProjectName()).getChildFile(Uuid().toString() + "_" + File::createLegalFileName(selectedFile.getFileName()));

    jassert(newFile.hasWriteAccess());  // No errors
    if(!selectedFile.copyFileTo(newFile))
    {
        DBG(__FUNCTION__ << " - Copy error: " << newFile.getFullPathName());
        return;
    }
    DBG(__FUNCTION__ << " - Copy success: " << newFile.getFullPathName());
}

As I said, this works on macOS.

5

Sadly on iOS especially with Files supporting ‘cloud’ documents you’ll need to use the InputStream and write it yourself.

I wish JUCE would have some nice async/threaded mechanism built-in. sadly currently there’s none.

So after you get the inputstream properly, write it to a fileoutputstream in your ‘sandboxed’ / app writable path(s).

1 Like
6

Thanks for your hint @ttg !

It works now on iOS and MacOS:

void AppSoundControls::fileChanged (juce::URL url)
{
    auto inputStream = url.createInputStream(false);
    if(inputStream == nullptr)
    {
        DBG(__FUNCTION__ << " - Error: Can't create inputStream ");
        return;
    }
    else
        DBG(__FUNCTION__ << " - Ok: inputStream created");
    
    juce::File newFile = FileHelpers::getProjectsDir().getChildFile(processor.getProjectState().getProjectName()).getChildFile(Uuid().toString() + "_" + File::createLegalFileName(url.getLocalFile().getFileName()));
    if(!newFile.hasWriteAccess())
    {
        DBG(__FUNCTION__ << " - Error: No write access ");
        return;
    }
    
    std::unique_ptr<juce::FileOutputStream> outputStream;
    outputStream = newFile.createOutputStream();
    outputStream->writeFromInputStream(*inputStream, inputStream->getTotalLength());
}
1 Like
7

To save someone else a bunch of wasted time debuging what’s wrong, be aware that File::copyFileTo will succeed on the iOS Similator but not on a real device.

Would be great to have the limitations of these functions documented.
Or even better not make them available on platforms where they don’t work.

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