How to add images while moving finger across UIView?

Question

I am having issues adding an image across a view while moving finger across the screen.

Currently it is adding the image multiple times but squeezing them too close together and not really following my touch.

EDIT:

What I want:

After taking or choosing an image, the user can then select another image from a list. I want the user to touch and move their finger across the view and the selected image will appear where they drag their finger, without overlapping, in each location.

This works:

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
     UITouch *touch = [touches anyObject];
     currentTouch = [touch locationInView:self.view];

     CGRect myImageRect = CGRectMake(currentTouch.x, currentTouch.y, 80.0f, 80.0f);
     myImage = [[UIImageView alloc] initWithFrame:myImageRect];
     [myImage setImage:[UIImage imageNamed:@"dot.png"]];
     [self.view addSubview:myImage];
     [myImage release];
}

New Question: How do I add spaces in this so that the image isn't so snug when drawing it on the view?

You want an image to move with user's finger when user has his/her finger moved on a view? — sunkehappy, Nov 06 '12 at 04:07
No. I want to add the image many times on the view while the user moves their finger. Think like your painting but instead of a solid color it's an image. — Luke Irvin, Nov 06 '12 at 04:15
Now I know what you mean, wait for me to write some code and test it. — sunkehappy, Nov 06 '12 at 04:23

score 0 · Answer 1 · answered Nov 06 '12 at 04:15

You might want to explain your question more, what exactly are you trying to achieve! If you dont want the images to overlap than you can try this!

UITouch * touch = [touches anyObject];
touchPoint = [touch locationInView:imageView];
prev_touchPoint = [touch previousLocationInView:imageView];

if (ABS(touchPoint.x - prev_touchPoint.x) > 80 
    || ABS(touchPoint.y - prev_touchPoint.y) > 80) {

   _aImageView = [[UIImageView alloc] initWithImage:aImage];
   _aImageView.multipleTouchEnabled = YES;
   _aImageView.userInteractionEnabled = YES;
  [_aImageView setFrame:CGRectMake(touchPoint.x, touchPoint.y, 80.0, 80.0)];
  [imageView addSubview:_aImageView];
  [_aImageView release];
}

sunkehappy · Answer 2 · 2012-11-06T05:12:17.307

I'm sorry because I'm in company and I can't post too big data(the code). The squeezing is because you have not checked the touch point's distance with last touch point. Check a point whether it's in a view:bool CGRectContainsPoint (CGRect rect,CGPoint point);I mean remember a touch point in touchesBegan:. Update it if the new touches in touchesMomved: is bigger than image's width or left. And put the add image view in a method and call it use - (void)performSelectorInBackground:(SEL)aSelector withObject:(id)arg.

score 0 · Answer 3 · edited May 18 '16 at 08:13

you can also use UISwipeGestureRecognizer as below instead of touchesMoved method,while swiping across the screen.in viewDidload:method,

UISwipeGestureRecognizer *swipeup = [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(swipedone:)];
swipeup.direction = UISwipeGestureRecognizerDirectionUp;
swipeup.numberOfTouchesRequired=1;
[self.view addGestureRecognizer:swipeup];

method definition:

-(IBAction)swipedone:(UISwipeGestureRecognizer*)recognizer
{
    NSLog(@"swiped");
    UIImageView* _aImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"1.png"]];
    _aImageView.frame = CGRectMake(10, 10, 100, 100);
    _aImageView.multipleTouchEnabled = YES;
    _aImageView.userInteractionEnabled = YES;
    CGPoint point = [recognizer locationInView:recognizer.view];
    [_aImageView setFrame:CGRectMake(point.x, point.y, 80.0, 80.0)];
    [self.view addSubview:_aImageView];
    [_aImageView release];
}

currently i am using this code for swipe up.i think it will works fine.once try it.

This has gotten me closer to what I want! How can I improve this to keep track of my finger and add the image at each new point it is at? — Luke Irvin, Nov 09 '12 at 07:37

How to add images while moving finger across UIView?

3 Answers3