Question

我正在开发一个应用程序，希望我的滚动视图在加载数据时锁定在适当的位置。当前，当用户刷新时，滚动视图立即恢复到原位。如何调整代码，使滚动视图锁定到位，直到完全执行其中的代码？到目前为止，这是我的代码：

@IBOutlet weak var scrollView: UIScrollView!
var refreshControl: UIRefreshControl!

@objc func refreshData(sender: UIRefreshControl){
    getItems()

    sender.endRefreshing()
}

这是我的getItems（）函数：

   func getItems() {
    //Hit the web service Url
    let serviceUrl = "omitted"
    let url = URL(string: serviceUrl)
    //Download the json data
    if let url = url{
        //Create a URL Session
        let session = URLSession(configuration: .default)
        let request = URLRequest(url: url, cachePolicy: .reloadIgnoringCacheData, timeoutInterval: 15.0)
        let task = session.dataTask(with: request, completionHandler: {(data, response, error) in
            if error == nil {
                //Succeeded
                //Call the parse json function on the data
                self.parseJson(data!)
            }
            else {
                print("error occured in getItems")
            }
        })
        // Start the task
        task.resume()
    }
}
//Parse it out into DataModel structs

func parseJson(_ data:Data){
    //parse the data into DataModel structs
    do{
        //parse the data into a json object
        let jsonArray = try JSONSerialization.jsonObject(with: data, options: []) as! [Any]
        //loop through each result in the json array
        for jsonResult in jsonArray {
            //Cast json result as a dictionary
            let jsonDict = jsonResult as! [String:String]
            //create new bar data and set its properties
            let bardata = DataModel(name: jsonDict["Bar Name"]!, cover: jsonDict["Bar Cover"]!, deals: jsonDict["Drink Deals"]!)
            //add it to the array
            bar_info.append(bardata)
        }
    }
    catch{
        print("There was an error")
    }
    //call function here
    update_cover()

}

func update_cover(){
    var a_cover = "$5"
    var b_cover = "$5"
    var c_cover = "$5"
    var d_cover = "$5"

    for item in bar_info{
        if item.name == "omitted"{
            a = item.cover
        }

        else if item.name == "omitted"{
            b_cover = item.cover
        }

        else if item.name == "omitted"{
            c_cover = item.cover
        }

        else if item.name == "omitted"{
            d_cover = item.cover
        }
    }


    DispatchQueue.main.async {
        self.aCoverView.text = a_cover
        self.bCoverView.text = b_cover
        self.cCoverView.text = c_cover
       self.dCoverView.text = d_cover
    }

}

Answer 1

要锁定滚动视图，请使用 scrollView.isUserInteractionEnabled = false ，然后解锁 scrollView.isUserInteractionEnabled = true

Answer 2

仅在重新滚动视图之前，存储当前位置的内容偏移量，然后在重新加载完成时对其进行设置。

var currentPos:CGPoint?

func reloadScrollview() { 
    currentPos = scrollview.contentOffset

    // do your reloading stuff
    // layout your subviews inside the scrollview
    // set the content size based upon your subviews

    scrollview.contentOffset = currentPos

}

快乐的编码。

Answer 3

听起来您正在实现“按需刷新”，所以我假设您将要使用#ifndef _WIN32_WINNT #define _WIN32_WINNT 0x601 #endif委托方法：

scrollViewDidScroll

现在，您只需要配置该方法。

Answer 4

您可以在getItems中执行以下操作：

    func getItems() {
        //Hit the web service Url
        let serviceUrl = "omitted"
        let url = URL(string: serviceUrl)
        //Download the json data
        if let url = url{
            //Create a URL Session
            let session = URLSession(configuration: .default)
            let request = URLRequest(url: url, cachePolicy: .reloadIgnoringCacheData, timeoutInterval: 15.0)
            let task = session.dataTask(with: request, completionHandler: {(data, response, error) in
                DispatchQueue.main.async {
                    self.refreshControl.endRefreshing()
                }
                if error == nil {
                    //Succeeded
                    //Call the parse json function on the data
                    self.parseJson(data!)
                }
                else {
                    print("error occured in getItems")
                }
            })
            // Start the task
            task.resume()
        }
    }

仅在网络请求完成后（即在完成处理程序中），刷新控件才需要结束刷新。由于请求是异步的，因此getItems在请求仍在进行时会立即返回。

刷新时锁定滚动视图？

4 个答案: