How to find when a tableView cell is touched or pinched in iphone?

Question

I have a tableView completed fill on view. when i tapped on a cell tableView:didSelectRowAtIndexPath: is getting fired, but when i wrote touchesBegan:withEvent to find touch and Pinch events of a tableView it was not fired. Tableview is above the view is that the reason of not firing, if yes how to find when tableView or its certain cell is touched or pinched.

---

I found a way to find Pinch Or touch in a Table View cell, declare UIPinchGestureRecognizer object first in tableView:didSelectRowAtIndexPath: i.e

UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(handlePinch:)];
[tblAccountsList addGestureRecognizer:pinch];
[pinch release];

then write the selector method below...

- (void)handlePinch:(UIGestureRecognizer *)recognizer {
    NSLog(@"Pinch");
}

when i set breakpoint it is executing, but the method was getting called for 3 times. If any one find the solution share it please...

Thanks in advance...

Answer 1

touchesBegan is a UIView and UITableViewCell method rather than a UIViewController & UITableViewController method. so you may create the the custom class for UITableViewCell it recognize the touch event and touch delegate it is working for me.

  //TableViewCell.h

#import <UIKit/UIKit.h>

@class Util;

@interface TableViewCell : UITableViewCell {

}
- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier;

@end
   //TableViewCell.m
#import "TableViewCell.h"
@implementation TableViewCell

-(id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier      format:(NSString*)ec_format{

    if (self) {
        self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];

   }

   return self;
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
 {
//you receive touch here 
    NSLog(@"Category Touch %@",self.frame);


}

In Table view you can add

- (void)viewDidLoad {

[super viewDidLoad];

// Add a pinch gesture recognizer to the table view.
UIPinchGestureRecognizer* pinchRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(handlePinch:)];
[self.tableView addGestureRecognizer:pinchRecognizer];

// Set up default values.
self.tableView.sectionHeaderHeight = HEADER_HEIGHT;
/*
 The section info array is thrown away in viewWillUnload, so it's OK to set the default values here. If you keep the section information etc. then set the default values in the designated initializer.
 */
rowHeight_ = DEFAULT_ROW_HEIGHT;
openSectionIndex_ = NSNotFound;
}


#pragma mark Handling pinches


-(void)handlePinch:(UIPinchGestureRecognizer*)pinchRecognizer {

/*
 There are different actions to take for the different states of the gesture recognizer.
 * In the Began state, use the pinch location to find the index path of the row with which the pinch is associated, and keep a reference to that in pinchedIndexPath. Then get the current height of that row, and store as the initial pinch height. Finally, update the scale for the pinched row.
 * In the Changed state, update the scale for the pinched row (identified by pinchedIndexPath).
 * In the Ended or Canceled state, set the pinchedIndexPath property to nil.
 */

if (pinchRecognizer.state == UIGestureRecognizerStateBegan) {

    CGPoint pinchLocation = [pinchRecognizer locationInView:self.tableView];
    NSIndexPath *newPinchedIndexPath = [self.tableView indexPathForRowAtPoint:pinchLocation];
    self.pinchedIndexPath = newPinchedIndexPath;

    SectionInfo *sectionInfo = [self.sectionInfoArray objectAtIndex:newPinchedIndexPath.section];
    self.initialPinchHeight = [[sectionInfo objectInRowHeightsAtIndex:newPinchedIndexPath.row] floatValue];
    // Alternatively, set initialPinchHeight = uniformRowHeight.

    [self updateForPinchScale:pinchRecognizer.scale atIndexPath:newPinchedIndexPath];
}
else {
    if (pinchRecognizer.state == UIGestureRecognizerStateChanged) {
        [self updateForPinchScale:pinchRecognizer.scale atIndexPath:self.pinchedIndexPath];
    }
    else if ((pinchRecognizer.state == UIGestureRecognizerStateCancelled) || (pinchRecognizer.state == UIGestureRecognizerStateEnded)) {
        self.pinchedIndexPath = nil;
    }
}
}


-(void)updateForPinchScale:(CGFloat)scale atIndexPath:(NSIndexPath*)indexPath {

if (indexPath && (indexPath.section != NSNotFound) && (indexPath.row != NSNotFound)) {

    CGFloat newHeight = round(MAX(self.initialPinchHeight * scale, DEFAULT_ROW_HEIGHT));

    SectionInfo *sectionInfo = [self.sectionInfoArray objectAtIndex:indexPath.section];
    [sectionInfo replaceObjectInRowHeightsAtIndex:indexPath.row withObject:[NSNumber numberWithFloat:newHeight]];
    // Alternatively, set uniformRowHeight = newHeight.

    /*
     Switch off animations during the row height resize, otherwise there is a lag before the user's action is seen.
     */
    BOOL animationsEnabled = [UIView areAnimationsEnabled];
    [UIView setAnimationsEnabled:NO];
    [self.tableView beginUpdates];
    [self.tableView endUpdates];
    [UIView setAnimationsEnabled:animationsEnabled];
}
}

Answer 2

It's being called 3 times because it's called each time the state of the gesture recogniser changes, not each time the gesture is recognised :)

Try this change :

- (void)handlePinch:(UIGestureRecognizer *)recognizer {
    if (recognizer.state == UIGestureRecognizerStateRecognized) {
        NSLog(@"Pinch");
    }
}

And check out the docs for gesture recognisers here, specifically the state property.