Drag and drop objects to their original position.

Question

I am trying to drag an image and return it to its original position after its release. For now, I can drag the image by creating it as a button using the following code: (as seen from the answer to this question: Basic drag and drop in iOS )

UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
[button addTarget:self action:@selector(imageTouch:withEvent:) forControlEvents:UIControlEventTouchDown];
[button addTarget:self action:@selector(imageMoved:withEvent:) forControlEvents:UIControlEventTouchDragInside];
[button setImage:[UIImage imageNamed:@"vehicle.png"] forState:UIControlStateNormal];
[self.view addSubview:button];

And later I define:

- (IBAction) imageMoved:(id) sender withEvent:(UIEvent *) event
{
    CGPoint point = [[[event allTouches] anyObject] locationInView:self.view];
    UIControl *control = sender;
    control.center = point;
}

How can I make it return to its original position after its release ?, for starters, I will save the position at which each image should return, but in any case there is an indication to indicate that UIImage should go from the current position and go to another? or any other alternative solution?

Answer 1

, , :

- (void)previewImageTouchUpInside:(UIButton*)aButton {
    if (!previewImageDragged) {
        [self selectPreviewImage:aButton];
        return;
}

    previewImageDragged = NO;

    // If user drag photo a little and then release, we'll still treat it as a tap
    //  instead of drag
    if ((originalPositionOfButton.x - aButton.center.x) * 
      (originalPositionOfButton.x - aButton.center.x) + 
      (originalPositionOfButton.y - aButton.center.y) * 
      (originalPositionOfButton.y - aButton.center.y) < 10) {
        aButton.center = originalPositionOfButton;
        [self selectPreviewImage:aButton];
        return;
    }

    [UIView animateWithDuration:0.5
        delay:0
        options:UIViewAnimationOptionCurveEaseOut |
        UIViewAnimationOptionAllowUserInteraction animations:^{
        aButton.center = originalPositionOfButton;
    } completion:nil];
}



- (void)previewImageDraggedInside:(UIButton*)aButton event:(UIEvent*)event {
    if (!previewImageDragged) {
        originalPositionOfButton = aButton.center;
        [self.view bringSubviewToFront:aButton];
        [self.view bringSubviewToFront:[self.view viewWithTag:CHOOSE_PHOTO_BUTTON_TAG]];
    }

    UITouch* touch = [[event allTouches] anyObject];

    previewImageDragged = YES;
    aButton.center = CGPointMake(aButton.center.x+[touch locationInView:self.view].x-
        [touch previousLocationInView:self.view].x, 
        aButton.center.y+[touch locationInView:self.view].y-
        [touch previousLocationInView:self.view].y);
}

, , . , .

Answer 2

UIGestureRecognizer Apple iOS. UIButton, UIView ( UIImageView ) .. .

:

@interface TestDragViewController : UIViewController {
    IBOutlet UIImageView *dragImage;
    CGPoint originalCenter;
}

viewDidLoad, plz userInteraction:

- (void)viewDidLoad {
    [super viewDidLoad];


    UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self 
                                                                                 action:@selector(dragGesture:)];
    [dragImage addGestureRecognizer:panGesture];
    [dragImage setUserInteractionEnabled:YES];
}

:

#pragma mark -
#pragma mark UIPanGestureRecognizer selector
- (void) dragGesture:(UIPanGestureRecognizer *) panGesture{
    CGPoint translation = [panGesture translationInView:self.view];

    switch (panGesture.state) {
        case UIGestureRecognizerStateBegan:{
            originalCenter = dragImage.center;
        }
            break;
        case UIGestureRecognizerStateChanged:{
            dragImage.center = CGPointMake(dragImage.center.x + translation.x,
                                           dragImage.center.y + translation.y);
        }
            break;
        case UIGestureRecognizerStateEnded:{            
            [UIView animateWithDuration:kImageReturnTime 
                             animations:^{
                                 dragImage.center = originalCenter;
                             }
                             completion:^(BOOL finished){
                                 NSLog(@"Returned");
                             }];
        }
            break;
        default:
            break;
    }

    [panGesture setTranslation:CGPointZero inView:self.view];
}

,

Tommy

Answer 3

CGPoint .h.

  CGPoint point;          

      UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
      [button addTarget:self action:@selector(imageTouch:withEvent:)forControlEvents:UIControlEventTouchDown];
      [button addTarget:self action:@selector(imageMoved:withEvent:) forControlEvents:UIControlEventTouchDragInside];
      [button setImage:[UIImage imageNamed:@"vehicle.png"] forState:UIControlStateNormal];
      [self.view addSubview:button];

:

- (IBAction) imageMoved:(UIButton*) sender withEvent:(UIEvent *) event
 {
point = [[[event allTouches] anyObject] locationInView:self.view];
UIControl *control = sender;
control.center = point;
 [sender addTarget:self action:@selector(touches:withEvent:) forControlEvents:UIControlEventTouchUpInside];
}

-(void)touches:(UIButton *)button withEvent:(UIEvent *)event {

[UIView animateWithDuration:0.1 delay:0 options:UIViewAnimationOptionCurveEaseOut | UIViewAnimationOptionAllowUserInteraction animations:^{
     button.center = point;

 } completion:^(BOOL finished){
     if (finished) {
    // do anything yu want
   }

, !

Answer 4

UIControlEventTouchUpInside, , x y (, ).

Answer 5

, , , , ( dropzone). , .

, iOS