find the distance between two CG points? - objective-c

Question

I am using these methods and these variables
CGPoint touchBegan;
CGPoint touchEnd;
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
}
- (void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
}
But I can not get the distance between two points. For example draw a line with your finger and get the distance between a CGPoint touchBegan and CGPoint touchEnd
Any help is appreciated thanks

Answer 1

It doesn't seem to exist any method or function that do this directly, you must take the difference of the two points coordinates and use pythagorean theorem:
CGPoint touchBegan;
CGPoint touchEnd;
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
UITouch* touch= [touches anyObject];
touchBegan= [touch locationInView: self.view];
}
- (void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch* touch= [touches anyObject];
touchEnd= [touch locationInView: self.view];
CGFloat dx= touchBegan.x - touchEnd.x;
CGFloat dy= touchBegan.y - touchEnd.y;
CGFloat distance= sqrt(dx*dx + dy*dy);
< Do stuff with distance >
}

Answer 2

Just implement your own rendition of the Pythagorean theorem. For example:
CGPoint translation = CGPointMake(endPoint.x - startPoint.x, endPoint.y - startPoint.y);
CGFloat distance = sqrtf(translation.x * translation.x + translation.y * translation.y);
Or, better, as Rob Mayoff pointed out, use the Math.h hypotf method:
CGFloat distance = hypotf(translation.x, translation.y);