Replacing image in UIScrollView on selected item - iphone

Question

I created simple UIScrollView that have images. Each time an image pressed i want to change that image, how can I do it?
I creating this UIScrollView and initializing it with NSMutableArray with images.
UIScrollView *myScroll = [[UIScrollView alloc] initWithFrame: CGRectMake (0,100,200,30)];
NSMutableArray = *images = [NSMutableArray alloc] initWithObjects: img1,img2,img3,nil];
for (int i=0; i<3; i++)
{
UIImageView *imageV = [UIImageView alloc];
[imageV setImage:[images objectAtIndex:i]];
[myScroll addSubview:imageV];
[imageV release];
}
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget: self action:#selector (changeImg:)];
[myScroll addGestureRecognizer: singleTap];
and the toucing I'm cathing with the touched place on the scroll:
- (void) singleTapGestureCaptured:(UITapGesturerecongnizer *) gesture
{
CGPoint touch = [gesture locationInView:myScroll];
}
By X,Y of touched item i know what image was selected
Here I need to change for example the first image of myScroll...How can i do it?

Answer 1

Add UITapGestureRecognizer on UIImageView and set its userInractionEnabled: YES which is NO by default for UIImageView.
UIScrollView *myScroll = [[UIScrollView alloc] initWithFrame: CGRectMake (0,100,200,30)];
NSMutableArray = *images = [NSMutableArray alloc] initWithObjects: img1,img2,img3,nil];
for (int i=0; i<3; i++)
{
//In your question you didn't set `imageView` frame so correct it
UIImageView *imageV = [[UIImageView alloc]initWithFrame:yourFrame];
[imageV setImage:[images objectAtIndex:i]];
[imageV setUserInteractionEnabled:YES];
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget: self action:#selector (changeImg:)];
[imageV addGestureRecognizer: singleTap];
[myScroll addSubview:imageV];
[imageV release];
}
After adding all imageView successfully you get them click like this :-
-(void)changeImg:(id)sender
{
UIGestureRecognizer *recognizer = (UIGestureRecognizer*)sender;
UIImageView *imageView = (UIImageView *)recognizer.view;
[imageView setImage:[UIImage imageNamed:#"anyImage.png"]];
}

Answer 2

Your application will crash because you are accessing the index 3, but there is not any object at index 3.
UIScrollView *myScroll = [[UIScrollView alloc] initWithFrame: CGRectMake (0,100,200,30)];
NSMutableArray = *images = [NSMutableArray alloc] initWithObjects: img1,img2,img3,nil];
[myScroll addSubview:[images objectAtIndex:0];
[myScroll addSubview:[images objectAtIndex:1];
[myScroll addSubview:[images objectAtIndex:2];
Now you can access the image view with tagValue
-(void)changeImg :(UIGestureRecognizer*)recog
{
UIScrollView *scroll = (UIScrollView*)recog.view;
CGPoint point = scroll.contentOffset;
int imagetag = (point.y/scroll.frame.size.height);
UIImageView *image=(UIImageView*)[[scroll subviews] objectAtIndex:imagetag];
NSLog(#"Image tag = %d",image.tag);
image.image=[UIImage imageNamed:#"Icon-72.png"];
}

Answer 3

A simple implementation will be, if you use a custom button and change its image on its IBAction.. Still you can addGesture to ur UIImageView too and on the
if(recognizer.state == UIGestureRecognizerStateBegan)
you can change the image on runtime.
I hope this helps. Cheers!!