iOS Swift - User Input and Forms
You want to create a UISlider that only allows values between 1 and 5, starting at 3, and prints "Selected: x" whenever the value changes. Which code snippet correctly implements this behavior?
You want to create a UISlider that only allows values between 1 and 5, starting at 3, and prints "Selected: x" whenever the value changes. Which code snippet correctly implements this behavior?
hard📝 Application Q15 of 15
Step-by-Step Solution
Solution:
Step 1: Check slider range and initial value
let slider = UISlider() slider.minimumValue = 1 slider.maximumValue = 5 slider.value = 3 slider.addTarget(self, action: #selector(valueChanged(_:)), for: .valueChanged) @objc func valueChanged(_ sender: UISlider) { print("Selected: \(sender.value)") } sets minimumValue to 1, maximumValue to 5, and initial value to 3, matching the requirements.Step 2: Verify target-action and method signature
let slider = UISlider() slider.minimumValue = 1 slider.maximumValue = 5 slider.value = 3 slider.addTarget(self, action: #selector(valueChanged(_:)), for: .valueChanged) @objc func valueChanged(_ sender: UISlider) { print("Selected: \(sender.value)") } uses .valueChanged event and an action method with sender parameter, correctly printing the slider's current value.Step 3: Identify errors in other options
let slider = UISlider() slider.minValue = 1 slider.maxValue = 5 slider.currentValue = 3 slider.addTarget(self, action: #selector(valueChanged), for: .touchUpInside) func valueChanged() { print("Selected: \(slider.value)") } uses incorrect property names and event type. let slider = UISlider(frame: CGRect(x: 0, y: 0, width: 100, height: 20)) slider.minimumValue = 0 slider.maximumValue = 10 slider.value = 3 slider.addTarget(self, action: #selector(valueChanged(_:)), for: .valueChanged) @objc func valueChanged(_ sender: UISlider) { print("Selected: \(sender.value)") } has wrong min/max values. let slider = UISlider() slider.minimumValue = 1 slider.maximumValue = 5 slider.value = 3 slider.addTarget(self, action: #selector(valueChanged), for: .valueChanged) @objc func valueChanged() { print("Selected: \(slider.value)") }'s action method lacks sender parameter.Final Answer:
Option A code snippet correctly implements the behavior -> Option AQuick Check:
Correct properties and action method = let slider = UISlider() slider.minimumValue = 1 slider.maximumValue = 5 slider.value = 3 slider.addTarget(self, action: #selector(valueChanged(_:)), for: .valueChanged) @objc func valueChanged(_ sender: UISlider) { print("Selected: \(sender.value)") } [OK]
Quick Trick: Use minimumValue, maximumValue, and action with sender param [OK]
Common Mistakes:
- Using wrong property names like minValue or currentValue
- Missing sender parameter in action method
- Using wrong control events like .touchUpInside
- Setting incorrect min/max values
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