Selecting images and then moving them - iphone

Question

I am trying to figure out how to select an object first then I am able to move it. For example I want to select cow first by touching it then I am able to move it. The reason being is when I am touching the screen it is moving both cow and cow1. When I only want to move one cow at a time. Any help will be appreciated.
-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [touches anyObject];
CGPoint touchLocation = [touch locationInView:touch.view];
cow.center = CGPointMake(touchLocation.x, touchLocation.y);
cow1.center = CGPointMake(touchLocation.x, touchLocation.y);
}

Answer 1

Try using UIPanGestureRecognizer, like this:
#synthesize myImage; //UIImageView
- (void)viewDidLoad
{
[super viewDidLoad];
[self startMoveImage];
}
-(void) startMoveImage{
UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(pan:)];
[self.view addGestureRecognizer:panGestureRecognizer];
}
- (void)pan:(UIPanGestureRecognizer *)gesture
{
if ((gesture.state == UIGestureRecognizerStateChanged) ||
(gesture.state == UIGestureRecognizerStateEnded)) {
CGPoint position = [gesture locationInView:[myImage superview]];
[myImage setCenter:position];
}
}

Answer 2

There are many ways to implement this sort of thing. It depends on how your graphics are implemented, amongst other things, check out this Apple sample code:
http://developer.apple.com/library/ios/#samplecode/Touches/Introduction/Intro.html

Answer 3

The standard solution would be to add separate gesture recognizers for your two cow objects, e.g., in viewDidLoad:
UIPanGestureRecognizer *panCow1 = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(moveCow:)];
[cow1 addGestureRecognizer:panCow1];
// if non ARC, make sure to add a line that says
// [panCow1 release];
UIPanGestureRecognizer *panCow2 = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(moveCow:)];
[cow2 addGestureRecognizer:panCow2];
// if non ARC, make sure to add a line that says
// [panCow2 release];
And then you have your moveCow method look something like:
- (void)moveCow:(UIPanGestureRecognizer *)sender
{
if (sender.state == UIGestureRecognizerStateChanged)
{
CGPoint translate = [sender translationInView:self.view];
sender.view.center = CGPointMake(sender.view.center.x + translate.x, sender.view.center.y + translate.y);
}
}
I haven't tested this code, but you get the idea. This is how I generally move separate subviews around...