Kann UIPinchGestureRecognizer und UIPanGestureRecognizer Zusammengeführt Werden?

6/14/14: Aktualisierter Beispielcode für iOS 7+ mit ARC.

Den UIGestureRecognizers zusammen arbeiten können, und Sie müssen nur sicherstellen, dass Sie don ' T trash der aktuellen Ansicht des transform-matrix. Verwenden Sie die CGAffineTransformScale-Methode und Verwandte Methoden, die verwandeln als Eingabe, anstatt es von Grund auf neu (es sei denn, Sie halten die aktuelle rotation, Skalierung oder translation selbst.

Download Xcode-Projekt

• Beispiel UIPinchGesture Projekt auf Github.

Hinweis: iOS 7 verhält sich komisch mit UIView ' s in IB, die Pan/Pinch/Rotate-gesten angewendet. iOS 8 behebt es, aber mein workaround ist, um alle Ansichten in code wie diesem code-Beispiel.

Demo-Video

1. Hinzufügen zu einer Ansicht und entsprechen den UIGestureRecognizerDelegate Protokoll

   @interface ViewController () <UIGestureRecognizerDelegate>
   
   @end
   
   @implementation ViewController
   
   - (void)viewDidLoad
   {
       [super viewDidLoad];
   
       UIView *blueView = [[UIView alloc] initWithFrame:CGRectMake(100, 100, 150, 150)];
       blueView.backgroundColor = [UIColor blueColor];
       [self.view addSubview:blueView];
       [self addMovementGesturesToView:blueView];
   
       //UIImageView's and UILabel's don't have userInteractionEnabled by default!
       UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"BombDodge.png"]]; //Any image in Xcode project
       imageView.center = CGPointMake(100, 250);
       [imageView sizeToFit];
       [self.view addSubview:imageView];
       [self addMovementGesturesToView:imageView];
   
       //Note: Changing the font size would be crisper than zooming a font!
       UILabel *label = [[UILabel alloc] init];
       label.text = @"Hello Gestures!";
       label.font = [UIFont systemFontOfSize:30];
       label.textColor = [UIColor blackColor];
       [label sizeToFit];
       label.center = CGPointMake(100, 400);
       [self.view addSubview:label];
       [self addMovementGesturesToView:label];
   }
   
   - (void)addMovementGesturesToView:(UIView *)view {
       view.userInteractionEnabled = YES;  //Enable user interaction
   
       UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePanGesture:)];
       panGesture.delegate = self;
       [view addGestureRecognizer:panGesture];
   
       UIPinchGestureRecognizer *pinchGesture = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(handlePinchGesture:)];
       pinchGesture.delegate = self;
       [view addGestureRecognizer:pinchGesture];
   }

2. Implementieren Geste Methoden

   - (void)handlePanGesture:(UIPanGestureRecognizer *)panGesture {
       CGPoint translation = [panGesture translationInView:panGesture.view.superview];
   
       if (UIGestureRecognizerStateBegan == panGesture.state ||UIGestureRecognizerStateChanged == panGesture.state) {
           panGesture.view.center = CGPointMake(panGesture.view.center.x + translation.x,
                                                panGesture.view.center.y + translation.y);
           //Reset translation, so we can get translation delta's (i.e. change in translation)
           [panGesture setTranslation:CGPointZero inView:self.view];
       }
       //Don't need any logic for ended/failed/canceled states
   }
   
   - (void)handlePinchGesture:(UIPinchGestureRecognizer *)pinchGesture {
   
       if (UIGestureRecognizerStateBegan == pinchGesture.state ||
           UIGestureRecognizerStateChanged == pinchGesture.state) {
   
           //Use the x or y scale, they should be the same for typical zooming (non-skewing)
           float currentScale = [[pinchGesture.view.layer valueForKeyPath:@"transform.scale.x"] floatValue];
   
           //Variables to adjust the max/min values of zoom
           float minScale = 1.0;
           float maxScale = 2.0;
           float zoomSpeed = .5;
   
           float deltaScale = pinchGesture.scale;
   
           //You need to translate the zoom to 0 (origin) so that you
           //can multiply a speed factor and then translate back to "zoomSpace" around 1
           deltaScale = ((deltaScale - 1) * zoomSpeed) + 1;
   
           //Limit to min/max size (i.e maxScale = 2, current scale = 2, 2/2 = 1.0)
           // A deltaScale is ~0.99 for decreasing or ~1.01 for increasing
           // A deltaScale of 1.0 will maintain the zoom size
           deltaScale = MIN(deltaScale, maxScale / currentScale);
           deltaScale = MAX(deltaScale, minScale / currentScale);
   
           CGAffineTransform zoomTransform = CGAffineTransformScale(pinchGesture.view.transform, deltaScale, deltaScale);
           pinchGesture.view.transform = zoomTransform;
   
           //Reset to 1 for scale delta's
           // Note: not 0, or we won't see a size: 0 * width = 0
           pinchGesture.scale = 1;
       }
   }
   
   - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
       return YES; //Works for most use cases of pinch + zoom + pan
   }

Ressourcen

• Xcode Geste Beispielprojekt
• Apples Gesten-Guide