objective-c adding UIGestureRcognizer to UIImageView in tableViewCell? - objective-c

Question

I have a UITableView with UITableViewCell which holds UIImageView's. Now I want to add a UILongGestureRecognizer to the UIImageView's. But this does not work. The UILongGestureRecognizer works on self.view...
How to implement the UILongGestureRecognizer that it works on the UIImageView's in the UITableViewCell's?
TableViewController.h
#interface MagTableViewController : UITableViewController <UIGestureRecognizerDelegate>
#property (strong, nonatomic) UILongPressGestureRecognizer *longPress;
#property (strong, nonatomic) NSMutableArray *tableContent;
#end
TableViewController.m
- (void)viewDidLoad
{
self.longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(longPressed:)];
self.longPress.minimumPressDuration = 0.2;
self.longPress.numberOfTouchesRequired = 1;
//[self.view addGestureRecognizer:self.longPress]; // This works!
}
// [...]
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
UIImageView *imvLeft = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 320, 100)];
[imvLeft setImageWithURL:[NSURL URLWithString:self.tableContent[#"url"]]];
imvLeft.userInteractionEnabled = YES; // added soryngod's hint, but does not
// solve the problem, as only the last row of 5 is enabled...
[imvLeft addGestureRecognizer:self.longPress]; // does not work...
[cell.contentView addSubview:imvLeft];
return cell;
}
-(void)longPressed:(UILongPressGestureRecognizer *)recognizer {
// do stuff
}

Answer 1

In addition to setting imvLeft.userInteractionEnabled = YES, you also need to make a distinct gesture recognizer for each image view. By design, UIGestureRecognizer must be associated with a single view. The symptoms you are seeing are a result of the recognizer being unattached from the previous cell as each new one calls addGestureRecognizer:.
See related question: Can you attach a UIGestureRecognizer to multiple views?

Answer 2

You need to set imvLeft.userInteractionEnabled = YES;
by default it is NO.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(longPressed:)];
longPress.minimumPressDuration = 0.2;
longPress.numberOfTouchesRequired = 1;
imvLeft.userInteractionEnabled = YES;
[imvLeft addGestureRecognizer:self.longPress];
[longPress release];
[cell.contentView addSubview:imvLeft];
return cell;
}
And if you want to identify the imageview that was pressed
-(void)longPressed:(UILongPressGestureRecognizer *)recognizer
{
UIImageView *img = (UIImageView *)recognizer.view;
//do stuff
}