Dragging a specific UIImageView - iphone

Question

In my code I have an array of objects which are UIImageViews with UIImages in them.
I use a for loop in -(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event to move all objects from the array one by one.
Once they are moved to different positions on the main view I would like to be able to grab any of those objects and move them somewhere else.
I'm not sure how best to do this. Is there a way I can use touchesbegin so that I can drag only the item I clicked on?
Basically, there are five UIImageViews there now and each one has UIImage and I am trying to get to the point where when i click on any of them they are able to move around.

Answer 1

EDIT: John Muchow posted this on a blog here. You should be able to adapt for your own purposes.
//UIDraggableImageView.h
#import <UIKit/UIKit.h>
#interface UIDraggableImageView : UIImageView
{
CGPoint currentPoint;
}
#end
//UIDraggableImageView.m
#import "UIDraggableImageView.h"
#implementation UIDraggableImageView
- (id)initWithImage:(UIImage *)image
{
if (self = [super initWithImage:image]) {
self.userInteractionEnabled = YES;
}
return self;
}
-(void)dealloc {
[super dealloc];
}
- (void) touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event
{
// When a touch starts, get the current location in the view
currentPoint = [[touches anyObject] locationInView:self];
}
- (void) touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event
{
// Get active location upon move
CGPoint activePoint = [[touches anyObject] locationInView:self];
// Determine new point based on where the touch is now located
CGPoint newPoint = CGPointMake(self.center.x + (activePoint.x - currentPoint.x),
self.center.y + (activePoint.y - currentPoint.y));
//--------------------------------------------------------
// Make sure we stay within the bounds of the parent view
//--------------------------------------------------------
float midPointX = CGRectGetMidX(self.bounds);
// If too far right...
if (newPoint.x > self.superview.bounds.size.width - midPointX)
newPoint.x = self.superview.bounds.size.width - midPointX;
else if (newPoint.x < midPointX) // If too far left...
newPoint.x = midPointX;
float midPointY = CGRectGetMidY(self.bounds);
// If too far down...
if (newPoint.y > self.superview.bounds.size.height - midPointY)
newPoint.y = self.superview.bounds.size.height - midPointY;
else if (newPoint.y < midPointY) // If too far up...
newPoint.y = midPointY;
// Set new center location
self.center = newPoint;
}
#end

Answer 2

I've done something similar with great success using the UIPanGestureRecognizer in my draggable view. To hook it up, it might look something like this:
#implementation DraggableView
-(id)initWithFrame:(CGRect)frame
{
...
...
UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(pan:)] autorelease];
[self addGestureRecognizer:panGesture];
..
return self;
}
#end
In your pan: method, you could check the state of the gesture and even capture the gesture's location and use it to relocate your view. Here's a rough example of what it might look like:
-(void)pan:(UIPanGestureRecognizer *)gesture
{
if (gesture.state==UIGestureRecognizerStateChanged)
{
//We're moving!
UIView *aRootView = <perhaps your root view controller's view>;
CGPoint currentOrigin = [gesture translationInView:aRootView];
self.frame = CGRectMake(currentOrigin.x,currentOrigin.y,self.frame.size.width,self.frame.size.hight);
...
...
}
}
Here is more reading on the UIPanGestureRecognizer.

Answer 3

You might want to consider adding gesture recognizers to the views that you want to move, that way you can easily tell when they are tapped and you can use touchesMoved to move them around...

Answer 4

On a button click add an image from camera roll to the imageview. Image can zoom in and out and should drag that image to any place in the view.