Is it possible to get the x and y coordinates of a touch?

Question

is it possible to get the x and y coordinates of a touch? If so could someone please provide a very simple example where the coordinates are just logged to the console.

Have you read the UITouch Class reference? – rdelmar Jul 18 '13 at 04:11 — rdelmar, Jul 18 '13 at 04:11

icodebuster · Accepted Answer · 2013-07-18T04:48:02.113

Using touchesBegan Event

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [[event allTouches] anyObject];
    CGPoint touchPoint = [touch locationInView:self.view];
    NSLog(@"Touch x : %f y : %f", touchPoint.x, touchPoint.y);
}

This event is triggered when touch starts.

Using Gesture

Register your UITapGestureRecognizer in viewDidLoad: Method

- (void)viewDidLoad {
    [super viewDidLoad];
    UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapGestureRecognizer:)];
    [self.view setUserInteractionEnabled:YES];
    [self.view addGestureRecognizer:tapGesture];
}

Setting up the tapGestureRecognizer function

// Tap GestureRecognizer function
- (void)tapGestureRecognizer:(UIGestureRecognizer *)recognizer {
    CGPoint tappedPoint = [recognizer locationInView:self.view];
    CGFloat xCoordinate = tappedPoint.x;
    CGFloat yCoordinate = tappedPoint.y;

    NSLog(@"Touch Using UITapGestureRecognizer x : %f y : %f", xCoordinate, yCoordinate);
}

Sample Project

Going off of the first method you gave, using the touches began, how can I make the x and y positions global variables? — AwesomeTN, Jul 18 '13 at 06:15
Create a CGPoint variable in your .h file and assign it in the above methoh — icodebuster, Jul 18 '13 at 06:50
The touches began work great, but I am unable to get touchesEnded to work, isn't almost the exact same thing? — AwesomeTN, Jul 18 '13 at 16:55

score 2 · Answer 2 · answered Jul 18 '13 at 04:13

First you need to add a gesture recognizer to the view you want.

UITapGestureRecognizer *myTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(myTapRecognizer:)];
[self.myView setUserInteractionEnabled:YES];
[self.myView addGestureRecognizer:myTap];

Then in the gesture recognizer method you make a call to locationInView:

- (void)myTapRecognizer:(UIGestureRecognizer *)recognizer
{
    CGPoint tappedPoint = [recognizer locationInView:self.myView];
    CGFloat xCoordinate = tappedPoint.x;
    CGFloat yCoordinate = tappedPoint.y;
}

You may want to take a look at apple's UIGestureRecognizer Class Reference

Ander · Answer 3 · 2013-07-18T05:46:17.543

0

Here's a very basic example (place it inside your view controller):

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    CGPoint currentPoint = [touch locationInView:self.view];
    NSLog(@"%@", NSStringFromCGPoint(currentPoint));
}

This triggers every time the touch moves. You can also use touchesBegan:withEvent: which triggers when a touch starts, and touchesEnded:withEvent: which triggers when a touch ends (i.e. a finger is lifted).

You can also do this using a UIGestureRecognizer, which in many cases is more practical.

edited Jul 18 '13 at 05:46

answered Jul 18 '13 at 04:02

Ander

3,688
1
22
24

I c/p this into my view controller and I got an error with the NSLog, but it was fixed by changing the string to NSSringFromCGPoint. But I still did not recieve anything in the console, am I missing something? Thanks for your help – AwesomeTN Jul 18 '13 at 05:37
You shouldn't have to add any extra code to make this work. Could something else be capturing the touch event (e.g. is there a subview like a button that could be stopping the touch from getting through to the viewController's view)? – Ander Jul 18 '13 at 05:48
Essentially, any view on added to the viewController's `self.view` that doesn't have `.userInteractionEnabled = NO` would capture the touch and stop it from going to the methods given in the answer above. – Ander Jul 18 '13 at 05:50

Is it possible to get the x and y coordinates of a touch?

3 Answers3

Linked