Question

我的CollectionView中有问题：

这里是viewWillAppear：

    override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)        

    let urlSession = URLSession(configuration: config)

    NSLog("Start URLSession")


    NSLog("Start Task")
    let task = urlSession.dataTask(with: url) { (data, response, error) in
        NSLog("task started")

        guard let data = data, error == nil else {
            print("error: \(String(describing: error))")

            //self.collectionView?.addSubview(blurView)
            //customActivityIndicatory(self.view)

            let alert = UIAlertController(title: "Error", message: "Connection Error", preferredStyle: .actionSheet)
            alert.addAction(UIAlertAction(title: "OK", style: .default) { action in
                // perhaps use action.title here
            })
            OperationQueue.main.addOperation {
                self.present(alert, animated: false)
            }

            return
        }

        do {
            guard let jsonData =  try? JSONSerialization.jsonObject(with: data, options: []) as! [String:Any] else {
                print("jsonError")
                return
            }
            //adressiere Array in JSON Dictionary
            self.Devs = jsonData["devices"] as! [[String:AnyObject]]

            NSLog("Json parsed")

            //Filter Array
            self.filteredArray = self.Devs.filter { self.devArray.contains($0["id"] as! String) }


            DispatchQueue.main.async {
                self.collectionView?.reloadData()

            }

        }

    }

    task.resume()

}

我有一个带有设备ID的数组：

    let devArray = defaults.mutableArrayValue(forKey: "savedDevs")

因此，让我们假装devArray中有4个ID。

我的numberOfItemsInSection看起来像这样：

override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

    return filteredArray.count
}

这里我必须使用filteredArray.count，因为当我启动App时会发生这种情况：

2017-09-05 16:21:51.411 [62695:2391013] notfirstStart
2017-09-05 16:21:51.437 [62695:2391013] Start URLSession
2017-09-05 16:21:51.453 [62695:2391013] Start Task
sections: 
numberOfItemsInSection:  0
2017-09-05 16:21:52.450 [62695:2391109] task started
2017-09-05 16:21:52.462 [62695:2391109] Json parsed
sections: 
numberOfItemsInSection:  4

问题是，在NSLOG＆＃34;开始任务后＃34;调用numberOfSections和numberOfItemsInSection的CollectionView函数。

此时，URL会话未完成且cellForItemAt崩溃，＆＃34;索引超出范围＆＃34;

我在这里做错了什么？

Answer 1

在获得响应后，在self.Devs = []中将您的数组viewWillAppear()清空self.Devs = jsonData["devices"] as! [[String:AnyObject]]并调用reloadData()方法。

URLSession和Collectionview时间

1 个答案: