Hello eskimo!
Thank you for the advices, they are super helpful and I'll be sure to implement them in my code!
However, I won't accept your answer, since the issue in my case was, that I was trying to call startAccessingSecurityScopedResource with a modified url (the folder that the user chose + NewFileName.extension). It kept returning false, no matter how I've modified the URL.
What worked for me, was calling startAccessingSecurityScopedResource with an unmodified folder url, that I receive from document picker.
Here I will leave a fully working example for future readers, to make their life easier:
- (void)openDocumentPicker
{
//This is needed, when using this code on QT!
//Find the current app window, and its view controller object
/*
UIApplication* app = [UIApplication sharedApplication];
UIWindow* rootWindow = app.windows[0];
UIViewController* rootViewController = rootWindow.rootViewController;
*/
//Initialize the document picker. Set appropriate document types
//When reading: use document type of the file, that you're going to read
//When writing into a new file: use @"public.folder" to select a folder, where your new file will be created
UIDocumentPickerViewController *documentPicker = [[UIDocumentPickerViewController alloc] initWithDocumentTypes:@[@"public.folder"] inMode:UIDocumentPickerModeOpen];
//Assigning the delegate, connects the document picker object with callbacks, defined in this object
documentPicker.delegate = self;
documentPicker.modalPresentationStyle = UIModalPresentationFormSheet;
//In this case we're using self. If using on QT, use the rootViewController we've found before
[self presentViewController:documentPicker animated:YES completion:nil];
}
- (void)documentPicker:(UIDocumentPickerViewController *)controller didPickDocumentsAtURLs:(NSArray<NSURL *> *)urls
{
//If we come here, user successfully picked a single file/folder
//When selecting a folder, we need to start accessing the folder itself, instead of the specific file we're going to create
if ( [urls[0] startAccessingSecurityScopedResource] ) //Let the os know we're going use this resource
{
//Write file case ---
//Construct the url, that we're going to be using: folder the user chose + add the new FileName.extension
NSURL *destURLPath = [urls[0] URLByAppendingPathComponent:@"Test.txt"];
NSString *dataToWrite = @"This text is going into the file!";
NSError *error = nil;
//Write the data, thus creating a new file. Save the new path if operation succeeds
if( ![dataToWrite writeToURL:destURLPath atomically:true encoding:NSUTF8StringEncoding error:&error] )
NSLog(@"%@",[error localizedDescription]);
//Read file case ---
NSData *fileData = [NSData dataWithContentsOfURL:destURLPath options:NSDataReadingUncached error:&error];
if( fileData == nil )
NSLog(@"%@",[error localizedDescription]);
[urls[0] stopAccessingSecurityScopedResource];
}
else
{
NSLog(@"startAccessingSecurityScopedResource failed");
}
}
