Flutter ZipFile.extractToDirectory doesn't overwrite existing files on iOS - ios

Question

I am using flutter_archive 4.0.1 (just updated to 4.1.1) and attempting to unzip a file into an existing directory.
My scenario is that I am backing up this folder, sending to a web server, then at some point, I will want to restore into the same folder. This folder will have many files that are the same filenames as in the zip. I need to overwrite the local files with the ones in the zip.
This works perfect on Android. iOS has always had problems when it comes to working with Zip files.
The extractToDirectory does not have an overwrite switch, so I attempted to use the onExtracting, to check if the file already exists locally, delete the local one, then allow the zip one to take its place.
The problem I am experiencing is that to check if it exists, and to delete, I have to use a Future, but as they are async, I cannot get them to synchronise.
Here is what I have tried.
if (Platform.isIOS) {
await ZipFile.extractToDirectory(
zipFile: zipFile,
destinationDir: destinationDir,
onExtracting: (zipEntry, progress) {
exists(zipEntry.name).then((value) {
if (value) {
deleteFile(zipEntry.name).then((value) {
return ZipFileOperation.includeItem;
});
} else {
return ZipFileOperation.includeItem;
}
});
return ZipFileOperation.includeItem;
}
);
}
Both exists and deleteFile are local Futures, that uses the File functionality.
What I have tried, is that the zipEntry.name will be the same as the file I need to overwrite, so this aspect should work fine. It is now just trying to make things work in order.
The Android version is the same, apart from it does not have the onExtracting functionality.

Answer 1

Not sure if you have found the answer or even if there is a good answer. I ran into this issue myself, and it seems the alternative is delete the target dir before unzipping. There seems no override option for unzip. Here is some snip bits about deletion (as also suggested by the package's unit test code):
final _appDataDir = Directory.systemTemp; //from dart.io
final destinationDir = Directory("${_appDataDir.path}/unzip");
if (destinationDir.existsSync()) {
print("Deleting existing unzip directory: ${destinationDir.path}");
destinationDir.deleteSync(recursive: true);
}
Hope this solution helps others who may have similar issues.