How to programmatically invoke the action of a `UISwitch`?

I have a UIViewController, in an SPM package, with a UITableView with some simple cells - they're either detail disclosures or have a UISwitch.

I'm trying to write unit tests to confirm that when the switch in a specific row is toggled, the desired action is invoked. That action was provided by other code, so the cell configuration looks like:

let toggle = UISwitch(frame: .zero, primaryAction: UIAction(handler: { action in
    guard let toggle = action.sender as? UISwitch else { return }
    toggleAction(toggle.isOn)
}))
cell.accessoryView = toggle

(where toggleAction was one of many passed to the VC's init)

My test can find the row of interest, and the switch on it. It can modify the value via .isOn, but that doesn't trigger the action. I am aware of the need for a UIApplication in order for .sendActions(for:) to work, so am using the solution here, and confirm that it works for UIButtons. I have tried sending various events to the UISwitch (.touchUpInside, .valueChanged, .primaryActionTriggered), but none of them cause the registered action to be invoked. Is it possible?

UISwitch is a UIControl. Since you setup the switch with a UIAction for the primary action, you can call sendActions on the switch:

let switch = ... // a reference to the UISwitch from the table cell
switch.isOn = true // or false as needed
switch.sendActions(for: .primaryActionTriggered)

This will result in the switch's action being called which in turn calls your toggleAction method.

No reference to the UIApplication is needed for this.

Here is some sample code that demonstrates that using sendActions works for both UISwitch and UIButton and that it works whether the control is setup with a primary action or with a target/selector.

The following can be run in an iOS Swift Playground.

class Controls {
    func toggleAction(_ isOn: Bool) {
        print("toggleAction: \(isOn)")
    }
    @objc func toggleHandler(_ sender: UIControl) {
        print("toggleHandler: \(sender)")
    }

    lazy var toggle = UISwitch(frame: .zero, primaryAction: UIAction(handler: { action in
        guard let toggle = action.sender as? UISwitch else { return }
        self.toggleAction(toggle.isOn)
    }))
    lazy var button = UIButton(primaryAction: UIAction(handler: { action in
        self.toggleAction(false)
    }))
    lazy var other = UIButton(type: .custom)

    func doStuff() {
        other.addTarget(self, action: #selector(toggleHandler), for: .touchUpInside)
        toggle.isOn.toggle()
        toggle.sendActions(for: .primaryActionTriggered)
        other.sendActions(for: .touchUpInside)
        button.sendActions(for: .primaryActionTriggered)
    }
}

let x = Controls()
x.doStuff()

The output will be something like:

>toggleAction: true
toggleHandler: <UIButton: 0x7fb77f406320; frame = (0 0; 0 0); opaque = NO; layer = <CALayer: 0x6000037e2fc0>>
toggleAction: false