How to give a specific gesture recognizer - ios

Question

When I apply panDetected like this, the image is moving everywhere on the screen. I just want this feature to at the top in specific rectangle. What should I change?
-(void) panDetected: (UIPanGestureRecognizer * ) panRecognizer {
CGPoint translation = [panRecognizer translationInView: self.documentImageView];
CGPoint imageViewPosition = self.documentImageView.center;
imageViewPosition.x += translation.x;
imageViewPosition.y += translation.y;
self.documentImageView.center = imageViewPosition;
[panRecognizer setTranslation: CGPointZero inView: self.view];
}
And this one is just allowing me to zoom on the pic but only from middle point not every point on the pic.
-(void) handlePinchWithGestureRecognizer: (UIPinchGestureRecognizer * ) pinchGestureRecognizer {
CGFloat lastScale = 1.0;
if ([pinchGestureRecognizer state] == UIGestureRecognizerStateBegan) {
// Reset the last scale, necessary if there are multiple objects with different scales
lastScale = [pinchGestureRecognizer scale];
}
if ([pinchGestureRecognizer state] == UIGestureRecognizerStateBegan || [pinchGestureRecognizer state] == UIGestureRecognizerStateChanged) {
CGFloat currentScale = [
[
[pinchGestureRecognizer view].layer valueForKeyPath: #
"transform.scale"] floatValue];
// Constants to adjust the max/min values of zoom
const CGFloat kMaxScale = 1.15;
const CGFloat kMinScale = 1.0;
CGFloat newScale = 1 - (lastScale - [pinchGestureRecognizer scale]);
newScale = MIN(newScale, kMaxScale / currentScale);
newScale = MAX(newScale, kMinScale / currentScale);
self.documentImageView.transform = CGAffineTransformScale(self.documentImageView.transform, newScale, newScale);
lastScale = [pinchGestureRecognizer scale]; // Store the previous scale factor for the next pinch gesture call
}
}
-(void) setExtractedImageForTableView: (UIImage * ) extractedImage {
self.documentImageView.image = nil;
self.documentImageView = nil;
self.documentImageView = [
[UIImageView alloc] initWithImage: extractedImage];
self.documentImageView.userInteractionEnabled = YES;
UIPinchGestureRecognizer * pinchGestureRecognizer = [
[UIPinchGestureRecognizer alloc] initWithTarget: self action: #selector(handlePinchWithGestureRecognizer: )];
[self.documentImageView addGestureRecognizer: pinchGestureRecognizer];
UIPanGestureRecognizer * panRecognizer = [
[UIPanGestureRecognizer alloc] initWithTarget: self action: #selector(panDetected: )];
[self.documentImageView addGestureRecognizer: panRecognizer];
self.documentImageView.contentMode = UIViewContentModeScaleAspectFit;
if (!CGSizeEqualToSize(extractedImage.size, CGSizeZero)) {
self.documentImageView.frame = CGRectMake(CGRectGetMinX(self.view.frame), CGRectGetMinY(self.tableView.frame), CGRectGetWidth(self.view.frame), (extractedImage.size.height / extractedImage.size.width) * CGRectGetWidth(self.view.frame));
self.tableView.tableHeaderView = self.documentImageView;
[self.tableView setContentOffset: CGPointZero animated: YES];
CGRect frame = self.documentImageView.frame;
frame.size.height = self.documentImageView.frame.size.height + 100;
self.tableView.frame = CGRectMake(0, 0, 200, 200);
self.tableView.tableHeaderView.frame = frame;
}
}

Answer 1

You can use UIGestureRecognizerDelegate to acheve this.
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
shouldReceiveTouch:(UITouch *)touch
The method above asks the delegate if a gesture recognizer should receive an object representing a touch. Therefore, you can check touch location and return NO when its not in the desired area.