How to bind Switch state to an object in Swift? - swift

Question

In my app I have a switch and I want it to be an indicator for saving images. For now I have just a button that saves all the images.
It just makes more sense with an example
What I've tried:
func saveTapped() {
let cell = collectionView?.cellForItem(at: indexPath) as! CustomCell
for image in images where cell.savingSwitch.isOn {
...
But I can't access indexPath. How should I call this Save method in order to access a particular row in my collectionView? Or is there another way?

Answer 1

First, you'll need a way to store the "save" settings alongside each image in your table, e.g. by keeping the image and the flag in a struct:
struct TableEntry {
let image: UIImage
var save = false
}
and use a var images: [TableEntry] in the data source of your tableview.
You can then use the tag property of each UISwitch to store the row it's in, e.g. in
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(...)
cell.switch.tag = indexPath.row
cell.switch.isOn = self.images[indexPath.row].save
cell.imageView.image = self.images[indexPath.row].image
return cell
}
and then use the tag in the method that's called when the switch value changes to know which image is being referred to:
#IBAction func switchChanged(_ sender: UISwitch) {
self.images[sender.tag].save = sender.isOn
}
func saveTapped() {
let imagesToSave = self.images.filter { $0.save }
}

Answer 2

In your CustomCell, you can add a closure to be fired when switch state is changed like below,
class CustomCell: UITableViewCell {
var onSwitchStateChange: ((Bool) -> Void)?
#IBAction func switchTapped(_ sender: UISwitch) {
self.onSwitchStateChange?(sender.isOn)
}
}
then you can update your cellForRowAt like below,
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
cell.onSwitchStateChange = { state in
guard state else { return }
let image = images[indexPath.row]
// Upload Image
}
}