How to access one controller variable and methods from other controller in swift correctly? - ios

Question

I create uiSegmentedControl in HomePageViewController. There are two items in segmented control. When I select first item , I add sensorItemViewController content as a subview in HomePageViewController with displayContentController method. And when clicked second item, I want to access methods of SensorTabItemViewController class which it's name is reloadMyTableView from HomePageViewConroller. I accessed from sensorItemVC but I get "unexpectedly found nil while unwrapping an Optional value" exception. How can access SensorItemTabViewController from HomePageViewControler correctly ? Thank you all response
HomePageViewController.swift :
let segmentedControlItems = ["Table", "RefreshTableView"]
var viewControllerArray: Array<UIViewController> = []
var segmentedControl : UISegmentedControl!
var sensorItemVC: SensorTabItemViewController!
class HomePageViewController: UIViewController,UIScrollViewDelegate {
override func viewDidLoad() {
super.viewDidLoad()
segmentedControl=UISegmentedControl(items: segmentedControlItems)
segmentedControl.selectedSegmentIndex=0
segmentedControl.tintColor=myKeys.darkBlueColor
segmentedControl.layer.cornerRadius = 0.0;
segmentedControl.layer.borderWidth = 1.5
segmentedControl.frame=CGRectMake(0, frameHeight/2, frameWidth, 35)
segmentedControl.addTarget(self, action: "changeSegmentedControlItem", forControlEvents: .ValueChanged)
self.view.addSubview(segmentedControl)
let sensorItemViewController = self.storyboard!.instantiateViewControllerWithIdentifier("sensorTabItemViewController")
viewControllerArray.append(sensorItemViewController)
}
func changeSegmentedControlItem(){
print(segmentedControl.selectedSegmentIndex)
if(segmentedControl.selectedSegmentIndex==0){
displayContentController(viewControllerArray[0])
}
else{
sensorItemVC.reloadMyTableView("Temp value", light: "Light value", noise: "noise Value", motion: "motion Value")
}
}
func displayContentController (content:UIViewController) {
self.addChildViewController(content)
print(self.segmentedControl.frame.height)
content.view.frame=CGRectMake(0, self.frameHeight/2+self.segmentedControl.frame.height, self.frameWidth,
self.frameHeight-(segmentedControl.frame.height*2+self.frameHeight/2))
self.view.addSubview(content.view)
content.didMoveToParentViewController(self)
}
}
SensorTabItemViewController. swift as below :
class SensorTabItemViewController: UIViewController,UITableViewDataSource,UITableViewDelegate {
#IBOutlet weak var tableView: UITableView!
let sensorName=["Sıcaklık Sensörü","Işık Sensörü","Gürültü Sensörü","Hareket Sensörü"]
var sensorDetails=["","","",""]
var sensorImages: Array<UIImage> = []
override func viewDidLoad() {
super.viewDidLoad()
print("sensorTab")
let tempImg=UIImage(named: "temp_ic") as UIImage?
let lightImg=UIImage(named: "light_ic") as UIImage?
let noiseImg=UIImage(named: "noise_ic") as UIImage?
let motionImg=UIImage(named: "motion_ic") as UIImage?
sensorImages.append(tempImg!)
sensorImages.append(lightImg!)
sensorImages.append(noiseImg!)
sensorImages.append(motionImg!)
// Do any additional setup after loading the view.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func reloadTableView(){
sensorDetails=[]
sensorDetails.append(temp)
sensorDetails.append(light)
sensorDetails.append(noise)
sensorDetails.append(motion)
tableView.reloadData()
}
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return sensorName.count
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("sensorCell", forIndexPath: indexPath) as UITableViewCell
cell.textLabel?.text=sensorName[indexPath.row]
cell.imageView?.image=sensorImages[indexPath.row]
cell.detailTextLabel?.text=sensorDetails[indexPath.row]
return cell
}
}

Answer 1

You never set the value of sensorItemVC. That is why it is nil. I guess that
let sensorItemViewController = self.storyboard!.instantiateViewControllerWithIdentifier("sensorTabItemViewController")
should be replaced with
sensorItemVC = self.storyboard!.instantiateViewControllerWithIdentifier("sensorTabItemViewController") as! SensorTabItemViewController