Get only files or only folders in a directory with Swiftydropbox

For example, this won't work, since the completion will be called too early:

func getSubDirectory(path: String, completion: @escaping ([String]) -> ()) {
        var directories: [String] = []
        if let client = DropboxClientsManager.authorizedClient {
            client.files.listFolder(path: path).response { response, error in
                if let result = response {
                    print("Folder contents:")
                    for entry in result.entries {
                        client.files.getMetadata(path: (entry.pathLower)!).response { response, error in
                            if let metadata = response {
                                if let folder = metadata as? Files.FolderMetadata {
                                    print(folder.name)
                                    directories.append(folder.name)
                                }
                            }
                        }
                    }
                    completion(directories)
                } else {
                    print(error!)
                }
            }
        }
    }

You don't need to call getMetadata for each entry. You can perform the as? Files.FolderMetadata or Files.FileMetadata check on each Metadata object in the entries list returned by listFolder itself.

I figured it out in the end, my solution ended up being like this:

func getFolders(path: String, completion: @escaping ([String]) -> ()) {
        var directories: [String] = []
        if let client = DropboxClientsManager.authorizedClient {
            client.files.listFolder(path: path).response { response, error in
                if let result = response {
                    for entry in result.entries {
                        if let folder = entry as? Files.FolderMetadata {
                            directories.append(folder.name)
                        }
                    }
                    directories.sort { $0.capitalized < $1.capitalized }
                    completion(directories)
                } else {
                    print(error!)
                }
            }
        }
    }