使用Swift在TableView中显示JSON数据

Question

I am trying to display some data I take from a data base into a TableView but the data is not shown in the TableView . The data I receive is formatted in JSON.

This is the data I receive form the data base and what I want to print in the TableView is just David:

{"name":"David"}

This is the code to get the data from de data base:

let session = NSURLSession.sharedSession()
    let request = NSURLRequest(URL: NSURL(string: "http://localhost:8888/Patients.php")!)
    let task = session.dataTaskWithRequest(request) {data, response, downloadError in

        if let error = downloadError {
            print("Could not complete the request \(error)")
        }
        else {

            do {
                self.json = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.AllowFragments)
            } catch {
                fatalError()
            }
            dispatch_async(dispatch_get_main_queue(), {

                if let parseJSON = self.json{

                    let name = parseJSON["name"] as! String

                    self.arrayData.append(name)

                    print("Data1:\(self.arrayData)")
                }

            })
        }
    }
    task.resume()

arrayData is an array where I put the data I receive from the data base and it is declared like this:

var arrayData: [String] = []

The code

print("Data1:\(self.arrayData)")

show in the console this Data1:["David"] , so I get the data correctly.

Then I implement the methods to print in the ´TableView´, the numberOfSectionsInTableView method, the numberOfRowsInSection method and the cellForRowAtIndexPath method but the data is not printed in the TableView .

I think the problem is that the TableView is drawn before I put the data in the array so it prints nothing because the array is empty, and I don´t know how to fix it.

Anyone knows what is my problem?

Answer 1

yes, you're right.

session.dataTaskWithRequest

is async. Data is not returned immediately, it have delay. You must to reload tableview after recieved data:

self.arrayData.append(name)
self.tableview.reloadData()

Usually i will use block:

func getData(handleComplete:((arr:NSMutableArray)->())){
    let aray = NSMutableArray()
    let session = NSURLSession.sharedSession()
    let request = NSURLRequest(URL: NSURL(string: "http://localhost:8888/Patients.php")!)
    let task = session.dataTaskWithRequest(request) {data, response, downloadError in

        if let error = downloadError {
            print("Could not complete the request \(error)")
        }
        else {

            do {
                self.json = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.AllowFragments)
            } catch {
                fatalError()
            }
            dispatch_async(dispatch_get_main_queue(), {

                if let parseJSON = self.json{

                    let name = parseJSON["name"] as! String

                    aray.append(name)

                    print("Data1:\(self.arrayData)")
                }
                handleComplete(aray)

            })
        }
    }
    task.resume()
    arrayData
}

and in viewdidload i will call:

override func viewDidLoad() {
    super.viewDidLoad()
    self.getData { (arr) -> () in
        self.tableview.reloadData()
    }
}

it 's better