Identifying which subview is tapped - iphone

Question

I have a background image (imageView - tag 0) which has been populated by several tagged image subviews (imgView - tagged 1 - ?). I have added a tap recognizer to the main background image, and also tried the subviews as well. I can get to the background tap recognizer routine by tapping, but am unable to identify which subview has been tapped.
Adding the tap recognizer to the background (during View did Load):
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(singleTapGestureCaptured:)];
[imageView addGestureRecognizer:singleTap];
[imageView setUserInteractionEnabled:YES];
Adding the tap recognizer to each subview as it is loaded:
- (void) showPics{ // display previously stored pictures
NSString *PictureName;
NSNumber *x;
NSNumber *y;
UIImage *viewImage;
tag = 1; // NSInteger declared in .h - background tag is zero
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(singleTapGestureCaptured:)];
NSLog(#"reading from picFile: %#",self.picFile);
if ([[NSFileManager defaultManager] fileExistsAtPath:self.picFile]){
NSLog(#"FILE Found");
NSMutableArray *picData;
picData = [[NSMutableArray alloc] initWithContentsOfFile:self.picFile];
int count = picData.count/3;
NSLog(#"Count: %d",count);
// set up picture path before cycling through array
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
// cycle to load pictures from file and place on background image
for(int i = 0; i < count; i++) {
PictureName = [picData objectAtIndex:i * 3];
NSString *showPic=[documentsDirectory stringByAppendingPathComponent:PictureName];
if ([[NSFileManager defaultManager] fileExistsAtPath:showPic]){
NSLog(#"Loading: %#",PictureName);
}else{
NSLog(#"Picture Does Not Exist");
}
x = [picData objectAtIndex:i * 3 + 1]; // x coord
y = [picData objectAtIndex:i * 3 + 2]; // y coord
viewImage = [UIImage imageWithContentsOfFile:showPic];
// find center of displayed image and place picture there
imgView = [[[UIImageView alloc] initWithFrame:CGRectMake([x floatValue] - 225,[y floatValue] - 172.5, 450, 345)] autorelease];
[imgView setImage:viewImage];
[imgView setContentMode:UIViewContentModeCenter];
[imgView addGestureRecognizer:singleTap];
[imgView setUserInteractionEnabled:YES];
imgView.tag = tag;
[imageView addSubview:imgView];
tag++;
NSLog(#"Tag: %d",tag);
}
[picData release];
}else{
NSLog(#"Did not find File");
}
}
The routine that is called with a tap anywhere:
- (void)singleTapGestureCaptured:(UITapGestureRecognizer *)sender{
NSLog(#"singleTapGestureCaptured - SUBVIEWS: %d", [imageView.subviews count]);
NSLog(#"TAG: %d",sender.view.tag);
}
This correctly gives me the number of subviews, but always returns "TAG: 0" unless I tap on the last added subview. What I need to know is the correct format for accessing the tapped subview's TAG so I can make it active and move it around, or any other suggestions as to how to do this.

Answer 1

I'm not sure enough to say that, but I guess the point is your tag variable doesn't change. If the tag variable is not global for the whole ".m" file, there's no way it saves its value within different functions or methods. Try declaring it in the ".h" file and give it some other name (ex. Tag or tagValue) so that the compiler could differ what it should return (the tag of a variable or your variable), then add self.Tagor self.tagValue (whatever you name it) every time you assign it to an int. Good luck and let me know if it works.

Answer 2

Put a breakpoint/NSLog the tag value of your imgView. The code snippet doesn't tell the scope of your tag variable (tag++). It seems it is not getting updated.
imgView.tag = tag;
Note, the sender.view in singleTapGestureCaptured method should always give your the topmost imgView (subview) since you are adding TapGestureRecognizer to all imgViews (subviews). In general, when the topmost subview doesn't add (register) any gesture in those cases the gesture passed on to the underlying subviews/parent views in order until someone handles it in the view stack.
EDIT: (After the additional code posted)
You need to create separate UITapGestureRecognizer object and add them to each subview. However all of them can use same #selector method.
So, move this line inside the for loop..
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(singleTapGestureCaptured:)];
just above
[imgView addGestureRecognizer:singleTap];

Answer 3

//I'm not fan of this but this worked for me
//you can create new imageView and pass tag of tapped subview
//for example some imageView that is subview of a view
//first:
UIImageView *imageView;
imageView.tag = 0;
UITapGestureRecognizer *itemTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(imageTap:)];
[imageView addGestureRecognizer:itemTap];
[someView addSubview:imageView];
//in the action selector imageTap:
-(void)imageTap:(id)sender{
if ([(UIGestureRecognizer *)sender view].tag == 0) {
UIImage *selectedImage;
selectedImage.frame = [[(UIGestureRecognizer *)sender view] viewWithTag:0].frame;
selectedImage.image = [UIImage imageNamed:#"newImage.png"];
//replace with the old:
[someView addSubview:selectedImage];
}}
GOODLUCK ;)