Swift API per convertire PNG in XLT

// For complete examples and data files, please go to https://github.com/aspose-cells-cloud/aspose-cells-cloud-swift/
    import AsposeCellsCloud
    let expectation1 = self.expectation(description: "checkAuth")
    AsposeCellsCloudAPI.clientId = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
    AsposeCellsCloudAPI.clientSecret = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
    AuthAspose.checkAuth()
    {
        (authError) in
        guard authError == nil else {
            XCTFail("error checkAuth")
            return
        }
        expectation1.fulfill()
    }
    self.waitForExpectations(timeout: testTimeout, handler: nil)        
    let expectation = self.expectation(description: "PutConvert")
    let workbook:String = "Book1.png"
    let format:String? = "xlt"     
    let url1: URL? = getURL(workbook)
    let filedata = NSData(contentsOfFile: url1!.path)
    let password:String? = nil
    let outPath:String? = nil
    CellsAPI.cellsWorkbookPutConvertWorkbook(file: url1!, format: format, password: password, outPath: outPath)
    {
        (response, error) in
        guard error == nil else {
            let errorinfo = self.GetErrorDataInfo(error: error as! ErrorResponse)
            print("error info: \(errorinfo!)")
            XCTFail("error PutConvert")
            return
        }            
        if let response = response {
            //response is a Data of file, we may write it down and check it.
            let fileName = "dest.xlt"
            let filePath = NSHomeDirectory()
            let fileManager = FileManager.default
            let path = "\(filePath)/tmp/\(fileName)"
            fileManager.createFile(atPath: path, contents:nil, attributes:nil)
            let handle = FileHandle(forWritingAtPath:path)
            handle?.write(response as Data)
            expectation.fulfill()
        }
    }
    self.waitForExpectations(timeout: testTimeout, handler: nil)