How to check whether a CGPoint is inside a UIImageView? - iphone

Question

In touchesBegan:
CGPoint touch_point = [[touches anyObject] locationInView:self.view];
There are tens of UIImageView around, stored in a NSMutableArray images. I'd like to know is there a built-in function to check if a CGPoint (touch_point) is inside one of the images, e.g.:
for (UIImageView *image in images) {
// how to test if touch_point is tapped on a image?
}
Thanks
Follow up:
For unknown reason, pointInside never returns true. Here is the full code.
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
touch_point = [touch locationInView:self.view];
for (UIImageView *image in piece_images) {
if ([image pointInside:touch_point withEvent:event]) {
image.hidden = YES;
} else {
image.hidden = NO;
}
NSLog(#"image %.0f %.0f touch %.0f %.0f", image.center.x, image.center.y, touch_point.x, touch_point.y);
}
}
although I can see the two points are sometimes identical in the NSLog output.
I also tried:
if ([image pointInside:touch_point withEvent:nil])
the result is the same. never returns a true.
To eliminate the chance of anything goes with with the images. I tried the following:
if (YES or [image pointInside:touch_point withEvent:event])
all images are hidden after the first click on screen.
EDIT 2:
Really weird. Even I hard coded this:
point.x = image.center.x;
point.y = image.center.y;
the code becomes:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint point; // = [touch locationInView:self.view];
for (UIImageView *image in piece_images) {
point.x = image.center.x;
point.y = image.center.y;
if ([image pointInside:point withEvent:event]) {
image.hidden = YES;
NSLog(#"YES");
} else {
image.hidden = NO;
NSLog(#"NO");
}
NSLog(#"image %.0f %.0f touch %.0f %.0f", image.center.x, image.center.y, point.x, point.y);
}
}
pointInside always returns false ...

Answer 1

Sounds to me like the problem is you need to convert coordinates from your view's coordinates to the UIImageView's coordinates. You can use UIView's convertPoint method.
Try replacing
if ([image pointInside:touch_point withEvent:event]) {
with
if ([image pointInside: [self.view convertPoint:touch_point toView: image] withEvent:event]) {
(Note that you are allowed to pass nil instead of event.)
I guess this is a bit late for the questioner, but I hope it is of use to someone.

Answer 2

if ([image pointInside:touch_point withEvent:event]) {
// Point inside
}else {
// Point isn't inside
}
In this case event is taken from :
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;

Answer 3

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint point = [touch locationInView:self.view];
for (UIImageView *piece in piece_images) {
CGFloat x_min = piece.center.x - (piece.bounds.size.width / 2);
CGFloat x_max = x_min + piece.bounds.size.width;
CGFloat y_min = piece.center.y - (piece.bounds.size.height / 2);
CGFloat y_max = y_min + piece.bounds.size.height;
if (point.x > x_min && point.x < x_max && point.y > y_min && point.y < y_max ) {
piece.hidden = YES;
} else {
piece.hidden = NO;
}
}
}
too bad, I have do it myself...
it's OS 3.2, XCode 3.2.2, tried both on simulator and iPad