Swift 3 adding selector issue on cell button - ios

Question

I have a custom button in my collection view cell. I just want to pass indexPath to it but I am getting
"unrecognized selector error"
Here is my code
cell.showMapButton.addTarget(self, action: #selector(testFunc(indexPath:)), for: .touchUpInside)
and the function is
func testFunc(indexPath: IndexPath){
print("Testing indexPath \(indexPath)")
}
If I remove the indexPath argument it works fine and the function gets called but I need that argument so please help me in resolving this issue.

Answer 1

In the addTarget(:action:for:) method for UIButton, the action can at most accept a single UIButton or any of it's superclass as parameter. If you need the indexPath of your button, you need to make it a property of your UIButton by subclass or other means. My way of doing it is to create a subclass of UIButton that have indexPath as it's property:
class ButtonWithIndexPath: UIButton {
var indexPath:IndexPath?
}
Then add target as normal:
cell.showMapButton.addTarget(self, action: #selector(testFunc(button:)), for: .touchUpInside)
Not forgetting to set the indexPath of your button to that of which ever cell it is in
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "myCell", for: indexPath) as! myCell
cell.button.indexPath = indexPath
...
return cell
}
And cast it into it's custom subclass in the function to read the indexPath:
func textFunc(button: UIButton) {
let currentButton = (button as! ButtonWithIndexPath)
print(currentButton.indexPath)
}

Answer 2

You can pass UIButton instance with target selector parameters for button action.
try with following code:
Add/replace below code, belongs to collection view cell into your collection view data source method - cellForRowAtIndexPath
cell.showMapButton.tag = indexPath.row
cell.showMapButton.addTarget(self, action: #selector(testFunc(button:)), for: .touchUpInside)
For Swift 4 - define your selector function using #objc, like below.
#objc func testFunc(button: UIBUtton){
print("Index = \(button.tag)")
}