Populate UITableView with JSON data

Question

I'm building a very basic reddit client for iPhone, just to practice developing for iOS. I've gotten it to parse the JSON of my selected subreddit, however I'm unable to take the titles from the parsed JSON and display them in my UITableView. The problem I'm having at the moment is that I can't get my "postList" array to populate with the JSON data before the UITableView is loaded. So when the table views cells are being populated, there's nothing in the postList array's elements for them to be populated with. Any idea how to fix this?

class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {

@IBOutlet weak var tableView: UITableView!

let URL = "https://www.reddit.com/r/swift/.json"

var postList : [PostList] = Array(repeating: PostList(), count: 26)
//var postList : [PostList] = []
override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    tableView.dataSource = self
    tableView.delegate = self
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.

}
//Setting up tableView
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return 5
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    var cell = tableView.dequeueReusableCell(withIdentifier: "aroundMeCell", for: indexPath)

    getPosts(url: URL, row: indexPath.row, cell: cell)
    let title = postList[indexPath.row].title
    cell.textLabel?.text = title
    return cell
}


//Receiving posts using Alamofire
func getPosts(url: String, row: Int, cell: UITableViewCell) {
    Alamofire.request(url, method: .get)
        .responseJSON { response in
            if response.result.isSuccess {
                let postJSON : JSON = JSON(response.result.value!)
                //print(postJSON)
                self.createPostListArray(json: postJSON, row: row, cell: cell)

            } else {
                print("Error: \(String(describing: response.result.error)) aaaaaa")
            }
    }
}

func createPostListArray(json: JSON, row: Int, cell: UITableViewCell) {

    let titlePath : [JSONSubscriptType] = ["data", "children", row, "data", "title"]
    let postPath : [JSONSubscriptType] = ["data", "children", row, "data", "selftext"]

    //Making sure I can unwrap both
    if(json[titlePath].string != nil && json[postPath].string != nil){
        let inTitle = json[titlePath].string!
        let inPost = json[postPath].string!
        postList[row].title = inTitle
        postList[row].post = inPost
    }
    else{
        print("error")
    }
}

Answer 1

There are multiple issues with your code.

1- var postList : [PostList] = Array(repeating: PostList(), count: 26). You can create empty array var postList = [PostList]() and append of delete element on response.

2- Calling an api on cellForRowAt is not at all a good idea. Reason : whenever this method gets called you call an api. Think about a scenario that you are scrolling your tableview for every dequeue you will call this api.

class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {

@IBOutlet weak var tableView: UITableView!

let URL = "https://www.reddit.com/r/swift/.json"

var postList = [PostList]()
override func viewDidLoad() {
    super.viewDidLoad()
    getPosts(url: URL)
    tableView.dataSource = self
    tableView.delegate = self
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.

}
//Setting up tableView
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return postList.count
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    var cell = tableView.dequeueReusableCell(withIdentifier: "aroundMeCell", for: indexPath)
    let title = postList[indexPath.row].title
    cell.textLabel?.text = title
    return cell
}


//Receiving posts using Alamofire
func getPosts(url: String) {
    Alamofire.request(url, method: .get)
    .responseJSON { [weak self] response in
        if response.result.isSuccess {
                    let postJSON : JSON = JSON(response.result.value!)
                //print(postJSON)
                self?.createPostListArray(json: postJSON)
                self?.tableView.reloadData()

            } else {
                print("Error: \(String(describing: response.result.error)) aaaaaa")
            }
    }
}

func createPostListArray(json: JSON) {
     //parse your json here, or read about objectMapper a pod. This will help you in parsing and if you are using swift 4, read encode json.
}

Answer 2

First do the api call in viewDidLoad() . Declare array as

      var postList = [PostList]

Perform self.tableview.reloadData() after api call success block.