How do I add images to a view by touch?

Question

I'm working on an image editing app. Right now I have the app built so a user can choose a photo from their library or take a photo with the camera. I also have another view (a picker view) that has other images a user can choose from. By selecting one of the images the app takes the user back to the main photo.

I want the user to be able to touch anywhere on screen and add the image they selected.

What is the best way to approach this?

touchesBegan? touchesMoved? UITapGestureRecognizer?

If anyone knows of any sample code or can give me a general idea of how to approach this that would be great!

EDIT:

Now I am able to see the coordinates and that my UIImage is getting the image I select from my Picker. But the image is not being displayed on the screen when I tap. Can someone help me troubleshoot my code please:

-(void)drawRect:(CGRect)rect
{    
    CGRect currentRect = CGRectMake(touchPoint.x, touchPoint.y, 30.0, 30.0);

    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextFillRect(context, currentRect);
}

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch * touch = [touches anyObject];
    touchPoint = [touch locationInView:imageView];

    NSLog(@"%f", touchPoint.x);
    NSLog(@"%f", touchPoint.y);

    if (touchPoint.x > -1 && touchPoint.y > -1) 
    {
        stampedImage = _imagePicker.selectedImage;   

        //[stampedImage drawAtPoint:touchPoint];

        [_stampedImageView setFrame:CGRectMake(touchPoint.x, touchPoint.y, 30.0, 30.0)];

        [_stampedImageView setImage:stampedImage];

        [imageView addSubview:_stampedImageView];

        NSLog(@"Stamped Image = %@", stampedImage);

        //[self.view setNeedsDisplay];
    }
}

For an example of my NSLogs I am seeing:

162.500000
236.000000
Stamped Image = <UIImage: 0xe68a7d0>

Thanks!

Answer 1

In your ViewController, user the method "-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event" to get the X and Y coordinate of where a touch happened. Here is some sample code that shows how to get the x and y of the touch

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 
{
    /* Detect touch anywhere */
    UITouch *touch = [touches anyObject];
    CGPoint touchPoint = [touch locationInView:self.view];

    NSLog(@"%f", touchPoint.x);  // The x coordinate of the touch
    NSLog(@"%f", touchPoint.y);  // The y coordinate of the touch
}

Once you have this x and y data, you can set the image that the user selected or shot with the built in camera to appear at those coordinates.

---

EDIT:

I think the issue MIGHT lie in how you create you UIImage view. Instead of this:

 -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch * touch = [touches anyObject];
    touchPoint = [touch locationInView:imageView];

    CGRect myImageRect = CGRectMake(touchPoint.x, touchPoint.y, 20.0f, 20.0f);
    UIImageView * myImage = [[UIImageView alloc] initWithFrame:myImageRect];
    [myImage setImage:_stampedImageView.image];
    myImage.opaque = YES;
    [imageView addSubview:myImage];
    [myImage release];
}

Try this:

 -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch * touch = [touches anyObject];
    touchPoint = [touch locationInView:imageView];

    myImage = [[UIImageView alloc] initWithImage:_stampedImageView.image];
    [imageView addSubview:myImage];
    [myImage release];
}

If this does not work, try checking if "_stampedImageView.image == nil". If this is true, Your UIImage may not have been created properly.