Download files with shared session

shared-session.js

function download(params) {
  params = params || {};
  params.handlers = params.handlers || {};

  const url = params.url;
  const method = params.method || "GET";
  const timeout = params.timeout || 60;
  const header = params.header || {};
  const body = params.body;
  const callback = params.handler;

  const request = $objc("NSMutableURLRequest").$requestWithURL($objc("NSURL").$URLWithString(url));
  request.$setHTTPMethod(method);
  request.$setTimeoutInterval(timeout);

  for (const [key, value] of Object.entries(header)) {
    request.$addValue_forHTTPHeaderField(value, key);
  }

  if (body) {
    request.$setHTTPBody(body.ocValue());
  }

  const session = $objc("NSURLSession").$sharedSession();
  const completionHandler = $block("void, NSURL *, NSURLResponse *, NSError *", (location, response, error) => {
    if (callback) {
      const data = $objc("NSData").$dataWithContentsOfURL(location).$copy();
      $thread.main({
        handler: () => {
          callback({
            "data": data.jsValue(),
            "response": response.jsValue(),
            "error": error.jsValue(),
          });
        }
      });
    }
  });

  const task = session.$downloadTaskWithRequest_completionHandler(request, completionHandler);
  task.$resume();
}

// exports.download = download;

download({
  "url": "https://www.apple.com/v/iphone/home/z/images/overview/the_ultimate_iphone_large_2x.jpg",
  "method": "GET",  // Optional, default to GET
  "timeout": 60,    // Optional, default to 60
  "header": {},     // Optional, default to {}
  "body": null,     // Optional, default to null
  "handler": result => {
    console.log(`Finished: ${JSON.stringify(result)}`);

    // props: data, response, error
    const data = result.data;
    if (data) {
      $share.sheet(data);
    }
  }
});