Gesture recognition (drag, magnify, rotate) in iOS Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is gesture recognition in iOS development?

Gesture recognition is the process of detecting and responding to user touch interactions like dragging, pinching to zoom (magnify), and rotating on the screen.

beginner

Which UIKit class is used to detect drag gestures?

UIPanGestureRecognizer is used to detect drag (pan) gestures where the user moves their finger across the screen.

beginner

How does UIPinchGestureRecognizer help in gesture recognition?

UIPinchGestureRecognizer detects pinch gestures, allowing the app to recognize when the user is zooming in or out by moving two fingers closer or farther apart.

beginner

What is the role of UIRotationGestureRecognizer?

UIRotationGestureRecognizer detects rotation gestures, letting the app know when the user rotates two fingers around a point on the screen.

intermediate

How do you add a gesture recognizer to a UIView in Swift?

You create a gesture recognizer instance, set its target and action, then add it to the UIView using addGestureRecognizer(). For example: view.addGestureRecognizer(panGesture).

Which gesture recognizer detects dragging motions?

A UITapGestureRecognizer

B UIPanGestureRecognizer

C UIRotationGestureRecognizer

D UIPinchGestureRecognizer

UIPanGestureRecognizer detects dragging or panning gestures.

What does UIPinchGestureRecognizer detect?

A Pinch to zoom

B Rotation

C Tap

D Swipe

UIPinchGestureRecognizer detects pinch gestures used for zooming in or out.

Which method adds a gesture recognizer to a view?

A addGesture()

B setGestureRecognizer()

C attachGesture()

D addGestureRecognizer()

addGestureRecognizer() is the correct method to add a gesture recognizer to a UIView.

UIRotationGestureRecognizer detects which type of gesture?

A Rotate

B Pinch

C Drag

D Tap

UIRotationGestureRecognizer detects rotation gestures.

What is the first step to use a gesture recognizer in Swift?

A Override the touch methods in UIView

B Call the gesture recognizer's start() method

C Create the gesture recognizer and set target/action

D Add gesture recognizer to the storyboard

You first create the gesture recognizer and set its target and action before adding it to a view.

Explain how to implement drag, magnify, and rotate gestures on a UIView in Swift.

Think about creating recognizers, adding them to the view, and updating the view's transform.

Describe the user experience improvements when adding gesture recognition to a mobile app.

Consider how users interact with touchscreens in real life.