I have two functions in a view controller. The first function parses JSON and makes an array; another generates a table with the array data. The problem is that it seems that the first function cannot send its array data to the second function.
Here is the code:-
class secondViewController: UIViewController, UITableViewDataSource {
let chartTitle:[String] = ["Name",......]
func parseJSON(){
let url = NSURL(string: "http://00000.us-west-2.elasticbeanstalk.com/index.php?000000")
let request = NSURLRequest(URL: url!)
do {
let data = try NSURLConnection.sendSynchronousRequest(request, returningResponse: nil)
do {
let json = try NSJSONSerialization.JSONObjectWithData(data, options: .MutableContainers)
var name = json["Name"]
var chartContent:[String] = ["\(name)",.....] //Contents of current chart contents
} catch{
//Handle Exception
}
} catch{
//Handle Exception
}
}
override func viewDidLoad() {
parseJSON()
...
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell { //currnet table information.
let cell = UITableViewCell()
cell.textLabel?.text = chartTitle[indexPath.row] + "\t\t\t\t\t here comes info" + chartContent[indexPath.row]
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return chartTitle.count
}
}
This code has an error at the tableView function:
Use of unresolved identifier 'chartContent'
I tried to declare the variables outside the first function which is right under the class secondViewController but there was another error on UITableViewDataSource.
Any solution for these?
Charttitle is defined outside any procedure, so it's available everywhere. Chartcontent is defined in a block, so it's usable just in it's block
Its because chartContent is a local variable just available to parseJson func only and its scope is till that func block. You have to create this variable the same way you dis chartTitle to be available throughout the class.
Related
I after asking another question today and fixed my Swift 4.2 code, I realized that I can't debug the app because of some profiles.
Errors shown when Testing application
The app also crashes on launch so there is not much I can do for now. I believe that the issue is how I am getting the information from the webserver (currently my computer). I am quite new to this, so i might have some mistakes in my code, so bear with me.
import UIKit
class InfoTableViewController: UITableViewController {
//MARK: Properties
class Produs {
var nume: String!
var codBare: String!
init(nume: String, codBare: String) {
self.nume = nume
self.codBare = codBare
}
}
var produse = [Produs]()
override func viewDidLoad() {
super.viewDidLoad()
//Load elements from server, theoretically
loadProducts()
}
// MARK: - Table view data source
override func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return produse.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
// Table view cells are reused and should be dequeued using a cell identifier.
let cellIdentifier = "InfoTableViewCell"
guard let cell = tableView.dequeueReusableCell(withIdentifier: cellIdentifier, for: indexPath) as? InfoTableViewCell else {
fatalError("The dequeued cell is not an instance of InfoTableViewCell.")
}
// Fetches the appropriate meal for the data source layout.
let produs = produse[indexPath.row]
cell.nameMain.text = produs.nume
cell.nameInfo.text = produs.codBare
return cell
}
// MARK: - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// Get the new view controller using segue.destination.
// Pass the selected object to the new view controller.
}
//MARK: Private Methods
private func loadProducts() { //This function retrieves information in a JSON format from the server
var request = URLRequest(url: URL(string: "192.168.0.145")!)
request.httpMethod = "GET"
URLSession.shared.dataTask(with: request, completionHandler: { data, response, error -> Void in
do {
let decoder = JSONDecoder()
let json = try decoder.decode([[String]].self, from: data!)
print(json)
for produs in json {
print(produs)
var nume_prod: String = produs[0] // Numele produsului
var cod_ext: String = produs[1] // Codul de bare al produsului
var prod_obj = Produs(nume: nume_prod, codBare: cod_ext)
self.produse.append(prod_obj)
}
} catch {
print("JSON Serialization error")
}
}).resume()
}
}
I am getting the information from the server in a JSON file that is an array of arrays and looks like this:
[
[
"product1",
"code1"
],
[
"product2",
"code2"
],
[
"product3",
"code3"
]
]
Thank you for your help!
Don't send the JSON as array of arrays, send it as array of dictionaries. It simplifies the decoding considerably.
[
{"name":"product1", "code":"code1"},
{"name":"product2", "code":"code2"},
{"name":"product3", "code":"code3"}
]
Then declare the model as struct and never declare properties as implicit unwrapped optional which are initialized with non-optional values. If you need optionals declare them as regular optional (?) otherwise non-optional
struct Produs {
let name: String
let code: String
}
Replace loadProducts with
private func loadProducts() { //This function retrieves information in a JSON format from the server
let url = URL(string: "192.168.0.145")!
URLSession.shared.dataTask(with: url, completionHandler: {[unowned self] data, response, error in
if let error = error { print(error); return }
do {
self.produse = try JSONDecoder().decode([Produs].self, from: data!)
print(self.produse)
DispatchQueue.main.async {
self.tableView.reloadData()
}
} catch {
print(error)
}
}).resume()
}
And replace cellForRowAt with
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cellIdentifier = "InfoTableViewCell"
let cell = tableView.dequeueReusableCell(withIdentifier: cellIdentifier, for: indexPath) as! InfoTableViewCell
// Fetches the appropriate meal for the data source layout.
let produs = produse[indexPath.row]
cell.nameMain.text = produs.name
cell.nameInfo.text = produs.code
return cell
}
I have researched this and nothing seems to be working. I am trying to build a recipe app and the the image of the dish & names of the dish (appetizer) are not downloading in order. How can I do this?
Code:
class Appetizers: UITableViewController {
var valueToPass: String!
var valuePassed: String!
var appetizer = [String]()
var images = [UIImage]()
func refresh() {
dispatch_async(dispatch_get_main_queue(), {
self.tableView.reloadData()
})
}
override func viewDidLoad() {
super.viewDidLoad()
// Parse - class - column
let query = PFQuery(className: "Appetizers")
query.orderByAscending("appetizer")
query.findObjectsInBackgroundWithBlock { (objects, error) -> Void in
if error == nil {
if let objects = objects {
for object in objects {
let load = object.objectForKey("appetizer") as! String
self.appetizer.append(load)
let imageFile = object["imageFiles"] as! PFFile
imageFile.getDataInBackgroundWithBlock({ (imageData: NSData?, error: NSError?) -> Void in
if error != nil {
print(error)
} else {
if let data = imageData {
self.images.append(UIImage(data: data)!)
self.tableView.reloadData()
}
}
})
self.tableView.reloadData()
}
}
} else {
print("Error: \(error!) \(error!.userInfo)")
}
}
sleep(1)
refresh()
}
override func viewWillAppear(animated: Bool) {
self.tableView.reloadData()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
// MARK: - Table view data source
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
// #warning Incomplete implementation, return the number of sections
return 1
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
// #warning Incomplete implementation, return the number of rows
return appetizer.count
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath)
cell.textLabel?.text = appetizer[indexPath.row]
// add image to table
if images.count > indexPath.row {
cell.imageView?.image = images[indexPath.row]
}
return cell
}
// when user taps on cell ...
func getCellLabel () {
let indexPath = tableView.indexPathForSelectedRow!
let currentCell = tableView.cellForRowAtIndexPath(indexPath) as UITableViewCell!
valueToPass = currentCell.textLabel!.text
}
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
getCellLabel()
self.performSegueWithIdentifier("0", sender: self)
}
}
When performing asynchronous queries, you have no assurances regarding the order they complete. So, the concept of two separate arrays, one an array of strings and another an array of images will always be problematic.
You could, for example, replace images with a dictionary indexed by the appetizer name, and thus it wouldn't matter what order they complete.
var appetizer = [String]()
var images = [String: UIImage]()
Thus, it might look like:
override func viewDidLoad() {
super.viewDidLoad()
let query = PFQuery(className: "Appetizers")
query.orderByAscending("appetizer")
query.findObjectsInBackgroundWithBlock { objects, error in
guard error == nil, let objects = objects else {
print(error)
return
}
for (index, object) in objects.enumerate() {
let appetizerName = object.objectForKey("appetizer") as! String
self.appetizer.append(appetizerName)
let imageFile = object["imageFiles"] as! PFFile
imageFile.getDataInBackgroundWithBlock { imageData, error in
guard error == nil, let data = imageData else {
print(error)
return
}
// when the image comes in, asynchronously update only that one row
self.images[appetizerName] = UIImage(data: data)
self.tableView.reloadRowsAtIndexPaths([NSIndexPath(forRow: index, inSection: 0)], withRowAnimation: .Fade)
}
}
// reload the table only once, after all of the `appetizer` entries are created (but likely before the images come in)
self.tableView.reloadData()
}
}
And
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath)
let name = appetizer[indexPath.row]
cell.textLabel?.text = name
cell.imageView?.image = images[name]
return cell
}
Or you could just replace these two separate properties with one that is an array of custom objects (e.g. an Appetizer object that has both a name property and an image property).
But any way you do that, you want to name sure you're not dealing with two separate array.
By the way, but this process of loading all of the images can be problematic if you have a lot of rows. This code is employing "eager" loading of images (loading them whether they're currently required or not). The problem is that images are relatively large assets (in comparison to the string values) and you can run into memory issues, network bandwidth issues, etc.
One generally likes to employ "lazy" loading (e.g. let cellForRowAtIndexPath request the image only when it's needed. For example, let's say you have 200 rows, of which only 12 are visible at one point. You shouldn't be requesting 200 images, but rather only that for the 12 visible ones. If you take the image retrieval out of viewDidLoad and, instead, have cellForRowAtIndexPath request them one at a time, you'll have much better network performance and less demanding memory characteristics.
If you're going to save the images in some structure like the code currently does, at the very least make sure you purge those images upon receiving notification of a memory warning (and, obviously, gracefully handle the re-requesting them in a JIT manner as needed).
I figured out the problem with my table not loading without sleep() ...
I had 'self.tableView.reloadData()' outside of the block.
Rob was very helpful :)
I am currently writing a small application that involves a tableView and an array of ManagedObjects for persistent storage.
What I want to do delete all the ManagedObjects in the array by clicking a button in another view controller.
To do this, I tried to make the array a static variable, unfortunately this conflicts with the methods that I use to populate the table with data from this array. Frustrating stuff.
Here is the code for the class:
class ClassOverviewController: UIViewController, UITableViewDataSource {
#IBOutlet weak var tableView: UITableView!
static var subjects = [NSManagedObject]()
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return subjects.count
}
static func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("Cell")
let subject = subjects[indexPath.row]
cell!.textLabel!.text = subject.valueForKey("subjectName") as? String
return cell!
}
static func clearSubjects() {
for item in (self.subjects)
{
CalculateClass.managedContext.deleteObject(item)
}
do {
try CalculateClass.managedContext.save()
}
catch let error as NSError {
print("Could not save \(error), \(error.userInfo)")
}
}
}
I have removed functions from the class that I did not think were necessary to show you.
It does not like me making the second tableView method static because I have taken that method from UITableViewDataSource.
I am unsure how I am supposed to proceed. Please help!
Go back to the non-static implementation so your table works.
When you want to remove the objects either:
get a reference to your ClassOverviewController object and call its method
or, if there's no connection between controllers, use a notification that tells the ClassOverviewController object that it should reset its array.
Assignment: "Create an application that displays a list of gas stations and their gas prices and distance. Store the information into a Dictionary. Display the results in a table view. Let the user select an entry and then display a UIAlert dialog showing the entry."
I am working on the dictionary part. The code for the dictionary is
"var gasStation = ["76": ["$2.76", "1.2 miles"],
"Arco":["$2.56", "2.4 miles"],
"Shell":["$3.54", "3.5 miles"],
"Tower mart": ["$2.36", "5.7 miles"]]"
The error pops up on this line of code
cell!.textLabel!.text = gasStation[indexPath.row]
Here is the New Updated code
import UIKit
class ViewController: UIViewController,UITableViewDataSource, UITableViewDelegate {
let dwarves = [ "Sleepy", "Sneezy", "bashful", "Happy"]
let gasStation = ["76": ["$2.76", "1.2 miles"],
"Arco":["$2.56", "2.4 miles"],
"Shell":["$3.54", "3.5 miles"],
"Tower-Mart": ["$2.36", "5.7 miles"]]
var gasStationNames = Array(gasStation) // error: "ViewController.Type' does not have a member named 'gasStation'
let simpleTableIdentifier = "SimpleTableIdentifier"
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func tableView(tableView: UITableView,
numberOfRowsInSection section: Int) -> Int {
return dwarves.count
}
func tableView(tableView: UITableView,
cellForRowAtIndexPath indexPath: NSIndexPath) ->UITableViewCell {
var cell = tableView.dequeueReusableCellWithIdentifier(
simpleTableIdentifier) as? UITableViewCell
if (cell == nil) {
cell = UITableViewCell(
style: UITableViewCellStyle.Default, reuseIdentifier: simpleTableIdentifier)
}
cell!.textLabel?.text = dwarves[indexPath.row]
return cell!
}
}
This is how you get an array of all the gas Station names.
let gasStationNames = Array(gasStation.keys)
But it will not be in the same order.
And for assigning it to the tableView:
cell!.textLabel!.text = gasStationNames[indexPath.row]
Here, you can index gasStationNames with indexPath.row of type Int as it is of type Array. And to get a value out of Dictionary, you should pass a key of proper type.
You should have a look at this document page
EDIT
Assign gasStationNames in your cellForRow
let gasStationNames = Array(gasStation.keys)
and then assign to cell's textLabel
cell!.textLabel!.text = gasStationNames[indexPath.row]
First question post for me. I would like to return a string from a function. The function should access a string (task.name) of the array (arrayOfTasks). The array looks to the index of a table to determine the value of task.name.
This is the error I'm getting when function callString is implemented: " Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid index path for use with UITableView. Index paths passed to table view must contain exactly two indices specifying the section and row. Please use the category on NSIndexPath in UITableView.h if possible.' "
As you can see, I tried to specify a section in the function (forSection...), but I continue to get the error.
func callString(var yzx: String, tableView: UITableView!, forRowAtIndexPath indexPath: NSIndexPath!, forSectionAtIndexPath: NSIndexPath!) -> String {
var task = arrayOfTasks[indexPath.row]
var yzx = task.name
return yzx
}
label.text = callString(String(), tableView: UITableView(), forRowAtIndexPath: NSIndexPath(), forSectionAtIndexPath: NSIndexPath())
You need to create a valid NSIndexPath.
Like this for example : NSIndexPath(forRow: 0, inSection: 0)
So you can change your function to something like this :
func callString(var yzx: String, tableView: UITableView!, forIndexPath indexPath: NSIndexPath!) -> String {
var task = arrayOfTasks[indexPath.row]
var yzx = task.name
return yzx
}
let label = UILabel()
label.text = callString(String(), UITableView(), forIndexPath: NSIndexPath(forRow: 0, inSection: 0))