How to get a CGPoint from a tapped location? - ios

Question

I'm working on a graphing calculator app for the iPad, and I wanted to add a feature where a user can tap an area in the graph view to make a text box pop up displaying the coordinate of the point they touched. How can I get a CGPoint from this?

Answer 1

you have two way ...
1.
-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [[event allTouches] anyObject];
CGPoint location = [touch locationInView:touch.view];
}
here,you can get location with point from current view...
2.
UITapGestureRecognizer *tapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapped:)];
[tapRecognizer setNumberOfTapsRequired:1];
[tapRecognizer setDelegate:self];
[self.view addGestureRecognizer:tapRecognizer];
here,this code use when you want to do somthing with your perticular object or subview of your mainview

Answer 2

Try This
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
// Get the specific point that was touched
CGPoint point = [touch locationInView:self.view];
NSLog(#"X location: %f", point.x);
NSLog(#"Y Location: %f",point.y);
}
You can use "touchesEnded" if you'd rather see where the user lifted their finger off the screen instead of where they touched down.

Answer 3

Just want to toss in a Swift 4 answer because the API is quite different looking.
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
if let touch = event?.allTouches?.first {
let loc:CGPoint = touch.location(in: touch.view)
//insert your touch based code here
}
}
OR
let tapGR = UITapGestureRecognizer(target: self, action: #selector(tapped))
view.addGestureRecognizer(tapGR)
#objc func tapped(gr:UITapGestureRecognizer) {
let loc:CGPoint = gr.location(in: gr.view)
//insert your touch based code here
}
In both cases loc will contain the point that was touched in the view.

Answer 4

it's probably better and simpler to use a UIGestureRecognizer with the map view instead of trying to subclass it and intercepting touches manually.
Step 1 : First, add the gesture recognizer to the map view:
UITapGestureRecognizer *tgr = [[UITapGestureRecognizer alloc]
initWithTarget:self action:#selector(tapGestureHandler:)];
tgr.delegate = self; //also add <UIGestureRecognizerDelegate> to #interface
[mapView addGestureRecognizer:tgr];
Step 2 : Next, implement shouldRecognizeSimultaneouslyWithGestureRecognizer and return YES so your tap gesture recognizer can work at the same time as the map's (otherwise taps on pins won't get handled automatically by the map):
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
shouldRecognizeSimultaneouslyWithGestureRecognizer
:(UIGestureRecognizer *)otherGestureRecognizer
{
return YES;
}
Step 3 : Finally, implement the gesture handler:
- (void)tapGestureHandler:(UITapGestureRecognizer *)tgr
{
CGPoint touchPoint = [tgr locationInView:mapView];
CLLocationCoordinate2D touchMapCoordinate
= [mapView convertPoint:touchPoint toCoordinateFromView:mapView];
NSLog(#"tapGestureHandler: touchMapCoordinate = %f,%f",
touchMapCoordinate.latitude, touchMapCoordinate.longitude);
}

Answer 5

If you use an UIGestureRecognizer or UITouch object you can use the locationInView: method to retrieve the CGPoint within the given view the user touched.

Answer 6

func handleFrontTap(gestureRecognizer: UITapGestureRecognizer) {
print("tap working")
if gestureRecognizer.state == UIGestureRecognizerState.Recognized {
`print(gestureRecognizer.locationInView(gestureRecognizer.view))`
}
}