Multiple touch problem using UITouch/UIView in iphone
- by John Qualis
Hi,
I am trying to implement a 2-finger "pinch" and "expand" (or enlarge) on a UIView using iPhone 3G and SDK 3.1.2. I haven't done programmed in UITouch/UIEvent before, so I appreciate any guidance to the problem I am facing.
When I touch the screen with 2 fingers I see that sometimes "touchesBegan" gives me only 1 event. I need UITouch event count == 2 to measure the distance between 2 fingers.
Hence I have to lift up my fingers and repeat this process again till I get both fingers to be detected. Is there a way around? Can I improve it?
The actual resize works correctly once both fingers are detected but this issue seen at the start needs to be resolved.
I know SDK 3.2 detects gestures such as pinch but I was wondering how it can be done in 3.1.2?
The code is given below. The "OnFingerDown" function gets called randomly even when I put 2 fingers down whereas I want "onTwoFingersDown" to be called each time. Moreover the I get only 1 touch event each time I put my fingers down. I mean if "OnFingerDown" was called twice I could somehow get it to work.
Thanks in advance. Appreciate any help.
John
- (void) touchesBegan: (NSSet*) touches withEvent: (UIEvent*) event
{
UITouch* touch, *touch1;
CGPoint location, location1;
if([[event allTouches] count] == 1) {
touch=[UI[[event allTouches] allObjects] objectAtIndex:0];
location=[touch locationInView:self];
OnFingerDown(location);
}
else if([[event allTouches] count] == 2) {
touch=[[[event allTouches] allObjects] objectAtIndex:0];
location=[touch locationInView:self];
touch1=[[[event allTouches] allObjects] objectAtIndex:1];
location1=[touch1 locationInView:self];
OnTwoFingersDown(location, location1);
}
}
