How do I detect it when I come back from Popover?
You can't use viewWillAppear, etc.
Run function during screen transition
swift
I tried to run the function when I dismissed by referring to , but when I tried to use the variable in the viewController on the return side, I got nil back.
Please let me know if anyone knows.
Code
override functableView(_tableView:UITableView, didSelectRowAtindexPath:IndexPath){
// Unselect Cells
tableView.deselectRow(at:indexPath, animated:true)
letback=storyboard!.instantiateViewController(withIdentifier: "View") as? ViewController
back?.doAnything (text:text [indexPath.row])
self.dismiss (animated: true, completion: {() in back?.received=self.text [indexPath.row]})
}
Another one
var number: Int!
func doAnything (text: String) {
print(text)
switch text {
case "1":
let activityItem: [Int] = number // This becomes nil
let activityVC = UIAactivityViewController (activityItems:activityItem, applicationActivities:nil)
self.present(activityVC, animated:true, completion:nil)
print(url)
case"2":
break
case "3":
break
case "4":
break
case "5":
break
default:
break
}
}
Just to confirm, I expect your code to look like this now.
Calling view controller:
class ViewController:UIViewController {
//...
// Assume Popover is displayed as `present` from some action method...
@ IBAction func someAction(_sender:Any){
//...
let storyboard = UIStoryboard (name: "Main", bundle:nil)
let popover=storyboard.instantiateViewController(withIdentifier: "Popover") as!PopoverViewController
//...
self.present(popover, animated:true, completion:nil)
}
var received —String?=nil
var number —Int!
func doAnything (text: String) {
print(text)
switch text {
case "1":
let activityItem: [Int] = [number] // <-`[number]`?
let activityVC = UIAactivityViewController (activityItems:activityItem, applicationActivities:nil)
self.present(activityVC, animated:true, completion:nil)
// print(url)//<- What is `url`?
case"2":
break
case "3":
break
case "4":
break
case "5":
break
default:
break
}
}
}
view controller for Popover:
class PopoverViewController:UITableViewController {
//...
var text: String = [ ]
override functableView(_tableView:UITableView, didSelectRowAtindexPath:IndexPath){
// Unselect Cells
tableView.deselectRow(at:indexPath, animated:true)
letback=storyboard!.instantiateViewController(withIdentifier: "View") as? ViewController
back?.doAnything (text:text [indexPath.row])
self.dismiss (animated: true, completion: {() in back?.received=self.text [indexPath.row]})
}
//...
}
There were some parts of the code you indicated that could not be compiled, so I have corrected it.It may have been rewritten a little to ask questions, but please be aware that the results may be fundamentally different.It also includes some estimates.If there are any significant differences, please let us know by adding information to your question or commenting.
So I think this is where your code is fatally incorrect.
letback=storyboard!.instantiateViewController(withIdentifier: "View") as? ViewController
You must not create a new instance to access the view controller that Popover returns to.This code creates a new instance (although it is in the same ViewController class), and the created instance is different from the view controller in "Return to".
There are many ways to do this, but the surest thing is to let Popover have the return view controller directly as a property.
Popover looks like this.
protocol PopoverViewControllerDelegate:class{
var received: String?{getset}
func doAnything (text: String)
}
class PopoverViewController:UITableViewController {
//...
weak vardelegate —PopoverViewControllerDelegate?
var text: String = [ ]
override functableView(_tableView:UITableView, didSelectRowAtindexPath:IndexPath){
// Unselect Cells
tableView.deselectRow(at:indexPath, animated:true)
delete?.doAnything (text:text[indexPath.row])
self.dismiss(animated:true){
self.delegate?.received=self.text [indexPath.row]
}
}
//...
}
This is a typical delete pattern, so the return destination is delegate and the features you want to invoke (methods and properties) are protocol.
This is what the caller will look like.
//↓Added conformity to `PopoverViewControllerDelegate`
classViewController:UIViewController, PopoverViewControllerDelegate{
//...
@ IBAction func someAction(_sender:Any){
//...
let storyboard = UIStoryboard (name: "Main", bundle:nil)
let popover=storyboard.instantiateViewController(withIdentifier: "Popover") as!PopoverViewController
popover.delegate=self//<- Set to delete when Popover is called
//...
self.present(popover, animated:true, completion:nil)
}
var received —String?=nil
var number —Int?//<- Do not use ImplicitlyUnwrappedOptions for variables that may not be initialized
func doAnything (text: String) {
Verify // `number` is non-nil with guard
guard let number = number else {
print("`number`is nil")
return
}
print(text)
//...
}
}
You should not use ImplicitlyUnwrappedOptions for variables such as number that may be uninitialized depending on the order of calls, so you should change it to a normal optional one and check non-nil with guard before using it.
As I wrote at the beginning, it contains some estimates, so I may have shown you something that is completely useless, but if you can apply it well to your code, please try it.
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