IOS development-Gesture Recognition (UIGestureRecognizer)

IOS development-Gesture Recognition (UIGestureRecognizer)
UIGestureRecognizer

The UIGestureRecognizer must be used to complete gesture recognition.

Using UIGestureRecognizer, you can easily identify some common gestures you make on a view.

UIGestureRecognizer is an abstract class that defines the basic behavior of all gestures. You can use its subclass to process specific gestures.

Merge // (strike) Merge // (pinch, used for scaling) UIPanGestureRecognizer // (drag and drop) Merge // (swipe) rotate // (rotate) UILongPressGestureRecognizer // (long press)

Hitting UITapGestureRecognizer

The usage of each gesture reader is similar. For example, the steps for using UITapGestureRecognizer are as follows:

Create a gesture identification object UITapGestureRecognizer * tap = [[UITapGestureRecognizer alloc] init]; set the attributes of the gesture recognition object // tap twice in a row. numberOfTapsRequired = 2; // you need two fingers to strike the tap together. numberOfTouchesRequired = 2; Add the gesture reader to the corresponding view [self. iconView addGestureRecognizer: tap]; listener [tap addTarget: self action: @ selector (tapIconView :)];

Hitting an instance

@ Interface GRViewController ()
  
   
@ Property (weak, nonatomic) IBOutlet UIImageView * iconView; @ end @ implementation GRViewController-(void) viewDidLoad {[super viewDidLoad]; [self testTap2];}-(void) testTap2 {UIGestureRecognizer * tap = [[UITapGestureRecognizer alloc] initWithTarget: self action: @ selector (tapView)]; tap. delegate = self; [self. iconView addGestureRecognizer: tap] ;}# pragma mark-proxy method/*** when you click view, this method is called first */-(BOOL) gest UreRecognizer :( UIGestureRecognizer *) gestureRecognizer shouldReceiveTouch :( UITouch *) touch {CGPoint pos = [touch locationInView: touch. view]; if (pos. x <= self. iconView. frame. size. width * 0.5) {return YES;} return NO;}-(void) testTap {// 1. create a gesture identification object UITapGestureRecognizer * tap = [[UITapGestureRecognizer alloc] init]; // The gesture can be recognized successfully after two consecutive strokes. numberOfTapsRequired = 2; tap. numberOfTouchesRequired = 2; // 2. add the gesture reader object to the corresponding view [self. iconView addGestureRecognizer: tap]; // 3. add a listening method (the corresponding gesture is recognized and the listening method is called) [tap addTarget: self action: @ selector (tapView)];}-(void) tapView {NSLog (@ "----- I tapped the screen !! ");} @ End
  

Long-pressed and lightly scanned instances

@ Interface GRViewController () @ property (weak, nonatomic) IBOutlet UIView * redView; @ end @ implementation GRViewController-(void) viewDidLoad {[super viewDidLoad]; UISwipeGestureRecognizer * swipe = [[UISwipeGestureRecognizer alloc] initWithTarget: self action: @ selector (swipeView)]; swipe. direction = uiswipegesturerecognizerdireup up; [self. redView addGestureRecognizer: swipe];}-(void) swipeView {NSLog (@ "swipeView");}-(void) testLongPress {login * longPress = [[using alloc] init]; [longPress addTarget: self action: @ selector (longPressView)]; // press longPress for at least 2 seconds. minimumPressDuration = 2; // before the gesture is triggered, press the valid longPress within the 50px range. allowableMovement = 50; [self. redView addGestureRecognizer: longPress];}-(void) longPressView {NSLog (@ "long pressed Red view");} @ end

Scaling and rotating instances

@ Interface GRViewController ()
  
   
@ Property (weak, nonatomic) IBOutlet UIImageView * iconView; @ end @ implementation GRViewController-(void) viewDidLoad {[super viewDidLoad]; [self testPinchAndRotate];} # pragma mark-proxy method of the gesture Reader/*** whether multiple gesture identifiers are allowed to work Simultaneously * Simultaneously: Simultaneously */-(BOOL) gestureRecognizer :( UIGestureRecognizer *) gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer :( UIGestureRecognizer *) otherGestureRecognizer {Return YES;} # pragma mark-zoom + rotate-(void) testPinchAndRotate {[self testPinch]; [self testRotate];} # pragma mark-zoom gesture (pinch gesture) -(void) testPinch {UIPinchGestureRecognizer * pinch = [[UIPinchGestureRecognizer alloc] initWithTarget: self action: @ selector (pinchView :)]; pinch. delegate = self; [self. iconView addGestureRecognizer: pinch];}-(void) pinchView :( UIPinchGestureRecognizer *) pinch {pinch. view. transfo Rm = CGAffineTransformScale (pinch. view. transform, pinch. scale, pinch. scale); pinch. scale = 1; // This is really important !!!!!} # Pragma mark-rotation gesture-(void) testRotate {UIRotationGestureRecognizer * recognizer = [[externalloc] initWithTarget: self action: @ selector (rotateView :)]; recognizer. delegate = self; [self. iconView addGestureRecognizer: recognizer];}-(void) rotateView :( UIRotationGestureRecognizer *) recognizer {recognizer. view. transform = CGAffineTransformRotate (recognizer. view. transform, recognizer. ro Tation); recognizer. rotation = 0; // This is very important !!!!!} @ End
  

Drag an instance

@ Interface GRViewController () @ property (weak, nonatomic) IBOutlet UIView * purpleView; @ end @ implementation GRViewController-(void) viewDidLoad {[super viewDidLoad]; UIPanGestureRecognizer * pan = [[UIPanGestureRecognizer alloc] initWithTarget: self action: @ selector (panView :)]; [self. purpleView addGestureRecognizer: pan];}-(void) panView :( UIPanGestureRecognizer *) pan {switch (pan. state) {case UIGestureRecognizerStateBegan: // start to trigger the gesture break; case UIGestureRecognizerStateEnded: // stop the gesture break; default: break;} // 1. the distance to CGPoint translation = [pan translationInView: pan. view]; CGPoint center = pan. view. center; center. x + = translation. x; center. y + = translation. y; pan. view. center = center; // 2. clear the distance of the Movement [pan setTranslation: CGPointZero inView: pan. view];} @ end

Gesture Recognition Status

Typedef NS_ENUM (NSInteger, UIGestureRecognizerState) {// no touch event occurs, default status of all Gesture Recognition is unknown, // when a gesture has started but has not been changed or completed, UIGestureRecognizerStateBegan, // The gesture status changes to UIGestureRecognizerStateChanged, // The gesture completes UIGestureRecognizerStateEnded, // The gesture is canceled and restored to the Possible status failed, // The gesture fails and is restored to the Possible status failed, // recognize the gesture recognition UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded };