self.tableView.reloadData ()가 Swift에서 작동하지 않습니다.

self.tableView.reloadData ()가 Swift에서 작동하지 않습니다.

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나는 동시에 개발 Swift의 기본과 배우려고 시도하고 iOS있으므로 저를 참아주세요. 내가있어 TableViewController먼저 로컬 구문 분석되는 JSON파일을하고에 아주 간단한 데이터의 렌더링 TableViewCell및 SectionHeaderViews을. 동일한 내에서 데이터를 반환 TableViewController하는 JSON끝점을 호출하고 있으며 ,이 데이터를 변수로 설정하여 실제로 얻고 자하는 항목에 액세스 할 수 있습니다 (API 구조가 바람직하지 않음). 그래서 마침내 적절한 데이터를 설정하고 self.tableData호출 self.tableView.reloadData()했지만 아무 일도 일어나지 않습니다. 무엇을 제공합니까?

import UIKit

class BusinessTableViewController: UITableViewController {

    var data: NSMutableData = NSMutableData()
    var tableData: NSArray = NSArray()

    @lazy var Business: NSArray = {
        let pathTCT = NSBundle.mainBundle().pathForResource("TCT", ofType: "json")
        let data = NSData.dataWithContentsOfFile(pathTCT, options: nil, error: nil)
        return NSJSONSerialization.JSONObjectWithData(data, options: nil, error: nil) as NSArray
        }()

    override func viewDidLoad() {
        super.viewDidLoad()

        navigationItem.titleView = UIImageView(image: UIImage(named: "growler"))

        tableView.registerClass(BeerTableViewCell.self, forCellReuseIdentifier: "cell")
        tableView.separatorStyle = .None

        fetchKimono()
    }

    override func numberOfSectionsInTableView(tableView: UITableView!) -> Int {
//        return Business.count
        return 1
    }

    override func tableView(tableView: UITableView?, numberOfRowsInSection section: Int) -> Int {
        let biz = Business[section] as NSDictionary
        let results = biz["results"] as NSDictionary
        let beers = results["collection1"] as NSArray
        return beers.count
    }

    override func tableView(tableView: UITableView?, cellForRowAtIndexPath indexPath: NSIndexPath?) -> UITableViewCell? {
        let cell = tableView!.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath!) as BeerTableViewCell
        if let path = indexPath {
            let biz = Business[path.section] as NSDictionary
            let results = biz["results"] as NSDictionary
            let beers = results["collection1"] as NSArray
            let beer = beers[path.row] as NSDictionary

            cell.titleLabel.text = beer["BeerName"] as String
        }

        return cell
    }

    override func tableView(tableView: UITableView!, titleForHeaderInSection section: Int) -> String! {
        let biz = Business[section] as NSDictionary
        return biz["name"] as String
    }

    override func tableView(tableView: UITableView!, viewForHeaderInSection section: Int) -> UIView! {
        let biz = Business[section] as NSDictionary
        let view = LocationHeaderView()
        view.titleLabel.text = (biz["name"] as String).uppercaseString
        return view
    }

    override func tableView(tableView: UITableView!, heightForHeaderInSection section: Int) -> CGFloat {
        return 45
    }

    func fetchKimono() {
        var urlPath = "names have been changed to protect the innocent"
        var url: NSURL = NSURL(string: urlPath)
        var request: NSURLRequest = NSURLRequest(URL: url)
        var connection: NSURLConnection = NSURLConnection(request: request, delegate: self, startImmediately: false)

        connection.start()
    }

    func connection(didReceiveResponse: NSURLConnection!, didReceiveResponse response: NSURLResponse!) {
        // Recieved a new request, clear out the data object
        self.data = NSMutableData()
    }

    func connection(connection: NSURLConnection!, didReceiveData data: NSData!) {
        // Append the recieved chunk of data to our data object
        self.data.appendData(data)
    }

    func connectionDidFinishLoading(connection: NSURLConnection!) {
        // Request complete, self.data should now hold the resulting info
        // Convert the retrieved data in to an object through JSON deserialization
        var err: NSError
        var jsonResult: NSDictionary = NSJSONSerialization.JSONObjectWithData(data, options:    NSJSONReadingOptions.MutableContainers, error: nil) as NSDictionary
        var results: NSDictionary = jsonResult["results"] as NSDictionary
        var collection: NSArray = results["collection1"] as NSArray
        if jsonResult.count>0 && collection.count>0 {
            var results: NSArray = collection as NSArray
            self.tableData = results
            self.tableView.reloadData()
        }
    }
}

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다음을 UI통해 스레드 에서 테이블을 다시로드해야합니다 .

//swift 2.3
dispatch_async(dispatch_get_main_queue(), { () -> Void in
    self.tableView.reloadData()
})

//swift 5
DispatchQueue.main.async{
    self.tableView.reloadData()
}

후속 조치 : connection.start()접근 방식에 대한 더 쉬운 대안 은NSURLConnection.sendAsynchronousRequest(...)

//NSOperationQueue.mainQueue() is the main thread
NSURLConnection.sendAsynchronousRequest(NSURLRequest(URL: url), queue: NSOperationQueue.mainQueue()) { (response, data, error) -> Void in
    //check error
    var jsonError: NSError?
    let json: AnyObject? = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.allZeros, error: &jsonError)
    //check jsonError
    self.collectionView?.reloadData()
}

예를 들어 bytesDownloaded / bytesNeeded를 통해 다운로드 진행률을 계산하고 싶을 수 있습니다.

---

다음을 입력하면됩니다.

먼저 IBOutlet :

@IBOutlet var appsTableView : UITableView

그런 다음 Action func에서 :

self.appsTableView.reloadData()

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연결이 백그라운드 스레드에있는 경우 다음과 같이 메인 스레드에서 UI를 업데이트해야합니다.

self.tblMainTable.performSelectorOnMainThread(Selector("reloadData"), withObject: nil, waitUntilDone: true)

내가 여기서 언급했듯이

스위프트 4 :

self.tblMainTable.performSelector(onMainThread: #selector(UICollectionView.reloadData), with: nil, waitUntilDone: true)

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제 경우에는 테이블이 올바르게 업데이트되었지만 이미지에 대해 setNeedDisplay ()가 호출되지 않았으므로 데이터가 다시로드되지 않는다고 잘못 생각했습니다.

---

그래서 문제는 @lazy를 부적절하게 사용하려고했기 때문에 비즈니스 변수가 본질적으로 상수가되어 편집 할 수 없게되었습니다. 또한 로컬 json을로드하는 대신 API에서 반환 된 데이터 만로드합니다.

import UIKit

class BusinessTableViewController: UITableViewController {

    var data: NSMutableData = NSMutableData()
    var Business: NSMutableArray = NSMutableArray()

    override func viewDidLoad() {
        super.viewDidLoad()

        navigationItem.titleView = UIImageView(image: UIImage(named: "growler"))

        tableView.registerClass(BeerTableViewCell.self, forCellReuseIdentifier: "cell")
        tableView.separatorStyle = .None

        fetchKimono()
    }

    override func numberOfSectionsInTableView(tableView: UITableView!) -> Int {
        return Business.count
    }

    override func tableView(tableView: UITableView?, numberOfRowsInSection section: Int) -> Int {
        if (Business.count > 0) {
            let biz = Business[section] as NSDictionary
            let beers = biz["results"] as NSArray
            return beers.count
        } else {
            return 0;
        }
    }

    override func tableView(tableView: UITableView?, cellForRowAtIndexPath indexPath: NSIndexPath?) -> UITableViewCell? {
        let cell = tableView!.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath!) as BeerTableViewCell
        if let path = indexPath {
            let biz = Business[path.section] as NSDictionary
            let beers = biz["results"] as NSArray
            let beer = beers[path.row] as NSDictionary

            cell.titleLabel.text = beer["BeerName"] as String
        } else {
            cell.titleLabel.text = "Loading"
        }

        return cell
    }

    override func tableView(tableView: UITableView!, viewForHeaderInSection section: Int) -> UIView! {
        let view = LocationHeaderView()
        let biz = Business[section] as NSDictionary
        if (Business.count > 0) {
            let count = "\(Business.count)"
            view.titleLabel.text = (biz["name"] as String).uppercaseString
        }
        return view
    }

    override func tableView(tableView: UITableView!, heightForHeaderInSection section: Int) -> CGFloat {
        return 45
    }

    func fetchKimono() {
        var urlPath = "names have been removed to protect the innocent"
        var url: NSURL = NSURL(string: urlPath)
        var request: NSURLRequest = NSURLRequest(URL: url)
        var connection: NSURLConnection = NSURLConnection(request: request, delegate: self, startImmediately: false)

        connection.start()
    }

    func connection(didReceiveResponse: NSURLConnection!, didReceiveResponse response: NSURLResponse!) {
        // Recieved a new request, clear out the data object
        self.data = NSMutableData()
    }

    func connection(connection: NSURLConnection!, didReceiveData data: NSData!) {
        // Append the recieved chunk of data to our data object
        self.data.appendData(data)
    }

    func connectionDidFinishLoading(connection: NSURLConnection!) {
        // Request complete, self.data should now hold the resulting info
        // Convert the retrieved data in to an object through JSON deserialization
        var err: NSError
        var jsonResult: NSDictionary = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) as NSDictionary
        var results: NSDictionary = jsonResult["results"] as NSDictionary
        var collection: NSArray = results["collection1"] as NSArray
        if jsonResult.count>0 && collection.count>0 {
            Business = jsonResult
            tableView.reloadData()
        }
    }
}

@lazy의 Swift Docs :

You must always declare a lazy property as a variable (with the var keyword), because its initial value may not be retrieved until after instance initialization completes. Constant properties must always have a value before initialization completes, and therefore cannot be declared as lazy.

---

Beside the obvious reloadData from UI/Main Thread (whatever Apple calls it), in my case, I had forgotten to also update the SECTIONS info. Therefor it did not detect any new sections!

---

All the calls to UI should be asynchronous, anything you change on the UI like updating table or changing text label should be done from main thread. using DispatchQueue.main will add your operation to the queue on the main thread.

Swift 4

DispatchQueue.main.async{
    self.tableView.reloadData()
}

---

You must reload your TableView in main thread only. Otherwise your app will be crashed or will be updated after some time. For every UI update it is recommended to use main thread.

//To update UI only this below code is enough
//If you want to do changes in UI use this
DispatchQueue.main.async(execute: {
    //Update UI
    self.tableView.reloadData()//Your tableView here
})

//Perform some task and update UI immediately.
DispatchQueue.global(qos: .userInitiated).async {  
    // Call your function here
    DispatchQueue.main.async {  
        // Update UI
        self.tableView.reloadData()  
    }
}

//To call or execute function after some time and update UI
DispatchQueue.main.asyncAfter(deadline: .now() + 5.0) {
    //Here call your function
    //If you want to do changes in UI use this
    DispatchQueue.main.async(execute: {
        //Update UI
        self.tableView.reloadData()
    })
}

---

I was also facing the same issue, what I did wrong was that I'd forgot to add

tableView.delegate = self    
tableView.dataSource = self

in the viewDidLoad() {} method. This could be one reason of self.tableView.reloadData() not working.

ReferenceURL : https://stackoverflow.com/questions/24112844/self-tableview-reloaddata-not-working-in-swift