How to call function from another ViewController - ios

Question

I am trying to call a function reloadTable in my HomeViewController from my Task class. But I keep being thrown an
Use of instance member 'reloadTable' on type 'HomeViewController'; did you mean to use a value of type 'HomeViewController' instead?
This is my HomeViewController code:
import UIKit
import Alamofire
import SwiftyJSON
class HomeViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
func reloadTable() {
self.displayTask.reloadData()
}
}
This is my Tasks class:
import Foundation
import Alamofire
import SwiftyJSON
class Tasks {
static let sharedInstance = Tasks()
var datas: [JSON] = []
func getTaskDetails(){
Alamofire.request(.GET, Data.weeklyEndpoint).validate().responseJSON { response in
switch response.result {
case .Success(let data):
let json = JSON(data)
if let buildings = json.array {
for building in buildings {
if let startDate = building["start_date"].string{
print(startDate)
}
if let tasks = building["tasks"].array{
Tasks.sharedInstance.datas = tasks
HomeViewController.reloadTable()
for task in tasks {
if let taskName = task["task_name"].string {
print(taskName)
}
}
}
}
}
case .Failure(let error):
print("Request failed with error: \(error)")
}
}
}
// for prevent from creating this class object
private init() { }
}

Answer 1

In this case reloadTable() is an instance method. You can't call it by class name, you have to create object for HomeViewController and then you have to call that method by using that object.
But in this situation no need to call the method directly by using HomeViewController object. You can do this in another way by using NSNotification
Using NSNotification :
Add a notification observer for your HomeViewController
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(HomeViewController.reloadTable), name:"ReloadHomeTable", object: nil)
Add the above lines in your viewDidLoad method of HomeViewController
Now replace this line HomeViewController.reloadTable() by NSNotificationCenter.defaultCenter().postNotificationName("ReloadHomeTable", object: nil) in your Task class

Answer 2

As many of the other answers states, you are trying to access a non-static function on a static reference.
I would suggest the use of closures, consider the following;
Create a closure for .Success and the .Failure, this enables you to act accordingly to the data request result. The onError closure is defined as an optional, this means you don't have to implement the onError in the ´getTaskDetails` function call, implement it where you feel you need the error information.
func getTaskDetails(onCompletion: ([Task]) -> (), onError: ((NSError) -> ())? = nil) {
Alamofire.request(.GET, Data.weeklyEndpoint).validate().responseJSON {
response in
switch response.result {
case .Success(let data):
let json = JSON(data)
if let buildings = json.array {
for building in buildings {
if let startDate = building["start_date"].string{
print(startDate)
}
if let tasks = building["tasks"].array{
Tasks.sharedInstance.datas = tasks
onCompletion(tasks)
}
}
}
case .Failure(let error):
print("Request failed with error: \(error)")
onError?(error)
}
}
}
From your HomeViewController:
// Call from wherever you want to reload data.
func loadTasks(){
// With error handling.
// Fetch the tasks and reload data.
Tasks.sharedInstance.getTaskDetails({
tasks in
self.displayTask.reloadData()
}, onError: {
error in
// Handle error, display a message or something.
print(error)
})
// Without error handling.
// Fetch the tasks and reload data.
Tasks.sharedInstance.getTaskDetails({
tasks in
self.displayTask.reloadData()
})
}
Basics
Closures

Answer 3

Make class Task as Struct, make function getTaskDetails as static and try to call function getTaskDetails() in HomeViewController. In result this of this function use realoadTable()

Answer 4

In HomeViewController you have defined reloadTable() as instance method not the class function.You should call reloadTable() by making instance of HomeViewController as HomeViewController(). Replace
HomeViewController.showLeaderboard()
HomeViewController().showLeaderboard()
Hope it helps. Happy Coding.