Title: Theory / Important / CS / Programming / Objective-C / Library / UIKit / Touch / Gesture
On every note of this deck, unless a note says otherwise:
Language: Objective-C

Typ: UIPreviewActionItem
Meaning: A set of methods that defines the styles you can apply to peek quick actions and peek quick action groups, and defines a read-only accessor for the user-visible title of a peek quick action.
Page: https://developer.apple.com/documentation/uikit/uipreviewactionitem?language=objc
Language: Objective-C

Variable: previewActionItem.title
Meaning: The peek quick action item’s title.
Page: https://developer.apple.com/documentation/uikit/uipreviewactionitem?language=objc
Language: Objective-C
Variables: UIPreviewActionItem previewActionItem

Typ: UIPreviewActionStyle
TypMeaning: The style for a peek quick action.
Page: https://developer.apple.com/documentation/uikit/uipreviewactionitem?language=objc
Language: Objective-C
Value: UIPreviewActionStyleDefault
The default style.
Value2: UIPreviewActionStyleSelected
The style for a selected peek quick action. Use this style for the initially-selected item within a disclosed peek quick action group.
Extra: Use these styles with instances of the UIPreviewAction and UIPreviewActionGroup classes.
Value3: UIPreviewActionStyleDestructive
The style for a peek quick action that changes or deletes data.

Instruction: [previewInteractionDelegate
  previewInteractionShouldBegin:previewInteraction
]
Page: https://developer.apple.com/documentation/uikit/uipreviewinteractiondelegate?language=objc
Returns: whether a preview interaction is allowed to begin.
Variables: UIPreviewInteractionDelegate previewInteractionDelegate

Instruction: [previewInteractionDelegate
  previewInteraction:previewInteraction
  didUpdatePreviewTransition:transitionProgress
  ended:ended
]
Page: https://developer.apple.com/documentation/uikit/uipreviewinteractiondelegate?language=objc
Effect: Informs the delegate of the progress through the preview phase of the preview interaction.
Variables: UIPreviewInteractionDelegate previewInteractionDelegate

Instruction: [previewInteractionDelegate
  previewInteraction:previewInteraction
  didUpdateCommitTransition:transitionProgress
  ended:ended
]
Page: https://developer.apple.com/documentation/uikit/uipreviewinteractiondelegate?language=objc
Effect: Informs the delegate of the preview interaction's progress through the commit phase.
Variables: UIPreviewInteractionDelegate previewInteractionDelegate

Instruction: [previewInteractionDelegate
  previewInteractionDidCancel:previewInteraction
]
Page: https://developer.apple.com/documentation/uikit/uipreviewinteractiondelegate?language=objc
Effect: Informs the delegate that the specified preview interaction was canceled.
Variables: UIPreviewInteractionDelegate previewInteractionDelegate

Typ: UIPreviewInteraction
Meaning: A class that registers a view to provide a custom user experience in response to 3D Touch interactions.
Page: https://developer.apple.com/documentation/uikit/uipreviewinteraction?language=objc
Language: Objective-C

Variable: previewInteraction.delegate
Meaning: An object that acts as the delegate of the preview interaction.
Page: https://developer.apple.com/documentation/uikit/uipreviewinteraction?language=objc
Language: Objective-C
Variables: UIPreviewInteraction previewInteraction

Variable: previewInteraction.view
Meaning: The view from which the preview interaction receives touch events.
Page: https://developer.apple.com/documentation/uikit/uipreviewinteraction?language=objc
Language: Objective-C
Variables: UIPreviewInteraction previewInteraction

Instruction: [view.previewInteraction
  initWithView:view
]
Page: https://developer.apple.com/documentation/uikit/uipreviewinteraction?language=objc
Returns: a newly initialized preview interaction for the specified view.
Variables: UIPreviewInteraction previewInteraction

Instruction: [view.previewInteraction
  cancelInteraction
]
Page: https://developer.apple.com/documentation/uikit/uipreviewinteraction?language=objc
Effect: Cancels the current preview interaction.
Variables: UIPreviewInteraction previewInteraction

Instruction: [view.previewInteraction
  locationInCoordinateSpace:coordinateSpace
]
Page: https://developer.apple.com/documentation/uikit/uipreviewinteraction?language=objc
Returns: the location of the touch that started the interaction.
Variables: UIPreviewInteraction previewInteraction

Typ: UIPreviewInteractionDelegate
Meaning: A set of methods for communicating the progress of a preview interaction.
Page: https://developer.apple.com/documentation/uikit/uipreviewinteractiondelegate?language=objc
Language: Objective-C

Name: A standard gesture
Definition: A gesture defined by iOS that user are expected to know and have a standard meaning
Page: https://developer.apple.com/design/human-interface-guidelines/ios/user-interaction/gestures/
Example: tap and double tap
Example2: drag, flick, touch and hold, rotate, shake
Example3: pinch and three finger pinch
Example4: swipe and three-finger swipe

Page: https://developer.apple.com/design/human-interface-guidelines/ios/user-interaction/gestures/
Effect: Rotates an image or view.
Context: iOS
Name: Rotation

Page: https://developer.apple.com/design/human-interface-guidelines/ios/user-interaction/gestures/
Context: iOS
Name: Touch and hold
Example: When performed in editable or selectable text, highlights the text under the fingertip and displays an edit menu.

Page: https://developer.apple.com/design/human-interface-guidelines/ios/user-interaction/gestures/
Effect: Initiate undo/redo when swiping left/right
Context: iOS
Name: Three finger swipe

Page: https://developer.apple.com/design/human-interface-guidelines/ios/user-interaction/gestures/
Effect: Copies selected text when pinching inward, pastes copied text when pinching outward.
Context: iOS
Name: Three finger pinch

Page: https://developer.apple.com/design/human-interface-guidelines/ios/user-interaction/gestures/
Effect: Zooms in when pinching outward, zooms out when pinching inward.
Context: iOS
Name: Pinch

Page: https://developer.apple.com/design/human-interface-guidelines/ios/user-interaction/gestures/
Effect: Zooms in and centers content or an image, or zooms out if already zoomed in.
Context: iOS
Name: double tap

Page: https://developer.apple.com/design/human-interface-guidelines/ios/user-interaction/gestures/
Effect: returns to the previous screen, reveals the hidden view in a split view controller, reveals the Delete button in a table-view row, or reveals actions in a peek. When performed with four fingers on an iPad, switches between apps.
Context: iOS
Name: Swipe

Page: https://developer.apple.com/design/human-interface-guidelines/ios/user-interaction/gestures/
Effect: Scrolls or pans quickly.
Context: iOS
Name: Flick

Page: https://developer.apple.com/design/human-interface-guidelines/ios/user-interaction/gestures/
Effect: Moves an element from side-to-side or drags an element across the screen.
Context: iOS
Name: Drag

Page: https://developer.apple.com/design/human-interface-guidelines/ios/user-interaction/gestures/
Effect: Activates a control or selects an item
Context: iOS
Name: Tap

Page: https://developer.apple.com/design/human-interface-guidelines/ios/user-interaction/gestures/
Effect: Initiates undo or redo.
Context: iOS
Name: Shake

Typ: UIGestureRecognizer
Meaning: The base class for concrete gesture recognizers.
Language: Objective-C
Intuition: decouples the logic for recognizing a sequence of touches (or other input) and acting on that recognition.

Name: A gesture recognizer
Definition: An object that allow to interpret a gesture and give abstraction with useful information to its user
Typ: UIGestureRecognizer

Name: A discrete gesture
Definition: A gesture that occurs but once in a multi-touch sequence and results in a single action sent.
Page: https://developer.apple.com/documentation/uikit/uigesturerecognizer?language=objc
Example: double tap,

Name: A continuous gesture
Definition: A gesture that sends an action message for each incremental change until the multi-touch sequence concludes.
Page: https://developer.apple.com/documentation/uikit/uigesturerecognizer?language=objc
Example: rotation gesture,