How to add only one tapGesture to image in UITableViewCell? - ios

Question

I have a tableView with custom cells. I have in one cell a imageView. I want add to this imageView one tapGesture for load a function then I click the imageView. So I have this code into cellForRowAtIndexPath:
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapDetected:)];
singleTap.numberOfTapsRequired = 1;
[cell.image setUserInteractionEnabled:YES];
[cell.image addGestureRecognizer:singleTap];
and
-(void)tapDetected:(id)sender{
NSLog(#"single Tap on imageview");
}
My problem is that when I scroll the table view this tap is added multiple times and changes into imageView then first click changes.
How can I change add only one time the tapGesture to all cells?

Answer 1

if you have a custom cell you can a function like this:
-(void) addTapGesture:(UITapGestureRecognizer*)tapGesture {
if (self.tapGesture == nil) {
[self.image setUserInteractionEnabled:YES];
[self.image addGestureRecognizer:singleTap];
self.tapGesture = tapGesture
}
}
in this way you are sure to set the tapGesture just once per cell.
Let me know if this can fix your problem

Answer 2

The Problem
Right now, you are adding a new TapGestureRecognizer every time cellForRowAtIndexPath is called, which is every time a cell is about to appear on the screen!
Solution 1: Keep the Old Gesture Recognizer
You can also just check if a cell already contains a gesture recognizer and not add a new one if it does. This will ensure that only one TapGestureRecognizer is applied to each cell:
// Check if the cell already contains a gesture recognizer
// if not, add one!
if (cell.gestureRecognizers.count == 0) {
// Now add the tap gesture recognizer and it will be the only one
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapDetected:)];
singleTap.numberOfTapsRequired = 1;
[cell.image setUserInteractionEnabled:YES];
[cell.image addGestureRecognizer:singleTap];
}
Note: You should probably check and make sure the cell contains
exactly the gesture recognizer that you desire- you may want to add
more gesture recognizers to your cells and then you'll have to make
sure it contains the right one!
Solution 2: Remove Gesture Recognizers
Remove all gesture recognizers from the cell before adding the TapGestureRecognizer. This will ensure that only one TapGestureRecognizer is applied to each cell:
// Removes all gesture recognizers in the cell
for (UIGestureRecognizer *recognizer in cell.gestureRecognizers) {
[cell removeGestureRecognizer:recognizer];
}
// Now add the tap gesture recognizer and it will be the only one
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapDetected:)];
singleTap.numberOfTapsRequired = 1;
[cell.image setUserInteractionEnabled:YES];
[cell.image addGestureRecognizer:singleTap];

Answer 3

just in you custom cell,do this :(i use swift as example)
class YourCell:UITableViewCell{
//add a variable to track has added a tapgesture to image view
var isAddedTapGesture = false
......
}
in your cellForRowAtIndexPath:
if(cell.isAddedTapGesture == false){
//add the tap gesture to your image
cell.cell.isAddedTapGesture = true
}

Answer 4

In your custom cell header, create a property like
#property (strong, nonatomic) UITapGestureRecognizer *tapGesture;
Add Getter method for the gesture.
- (UITapGestureRecognizer*)tapGesture{
if (!_tapGesture) {
_tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapDetected:)];
}
return _tapGesture;
}
and inside the awakeFomNib function, Remove and re - add the gesture for the image view like the below.
[self.image removeGestureRecognizer:self.tapGesture];
[self.image addGestureRecognizer:self.tapGesture];
Hope this will be helpfull.