[Solved] You want to create a toggle switch that updates a label text to "ON" or "OFF" when toggled.... let toggle = UISwitch() let label = UILabel() // Which switchChanged method is correct? | iOS Swift

iOS Swift - User Input and Forms

You want to create a toggle switch that updates a label text to "ON" or "OFF" when toggled. Which code snippet correctly implements this behavior?

let toggle = UISwitch()
let label = UILabel()

// Which switchChanged method is correct?

A@objc func switchChanged(_ sender: UISwitch) { label.text = sender.isOn ? "ON" : "OFF" }

B@objc func switchChanged() { label.text = toggle.isOn ? "ON" : "OFF" }

C@objc func switchChanged(_ sender: UISwitch) { if sender.isOn == false { label.text = "ON" } else { label.text = "OFF" } }

D@objc func switchChanged(_ sender: UISwitch) { label.text = "ON" }

Step-by-Step Solution

Solution:

Step 1: Check method signature and parameter
The action method must accept the sender UISwitch to get its current state.
Step 2: Verify label text update logic
@objc func switchChanged(_ sender: UISwitch) { label.text = sender.isOn ? "ON" : "OFF" } uses a ternary operator to set label text to "ON" if switch is on, else "OFF", which is correct.
Step 3: Review other options
@objc func switchChanged() { label.text = toggle.isOn ? "ON" : "OFF" } lacks sender parameter; @objc func switchChanged(_ sender: UISwitch) { if sender.isOn == false { label.text = "ON" } else { label.text = "OFF" } } reverses ON/OFF logic; @objc func switchChanged(_ sender: UISwitch) { label.text = "ON" } always sets "ON" ignoring switch state.
Final Answer:
@objc func switchChanged(_ sender: UISwitch) { label.text = sender.isOn ? "ON" : "OFF" } -> Option A
Quick Check:
Use sender.isOn with ternary to update label [OK]

Quick Trick: Use sender.isOn ? "ON" : "OFF" to update label [OK]

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You want to create a toggle switch that updates a label text to "ON" or "OFF" when toggled. Which code snippet correctly implements this behavior?