Overview

When one or more fingers touch the screen, move around or are raised, an SPTouchEvent is triggered.

The event contains a list of all touches that are currently present. Each individual touch is stored in an object of type “Touch”. Since you are normally only interested in the touches that occurred on top of certain objects, you can query the event for touches with a specific target through the touchesWithTarget: method. In this context, the target of a touch is not only the object that was touched (e.g. an SPImage), but also each of its parents - e.g. the container that holds that image.

Here is an example of how to react on touch events at ‘self’, which could be a subclass of SPSprite:

// e.g. in 'init'
[self addEventListener:@selector(onTouch:) atObject:self forType:SPEventTypeTouch];

// the corresponding listener:
- (void)onTouch:(SPTouchEvent *)event
{
    // query all touches that are currently moving on top of 'self'
    NSArray *touches = [[event touchesWithTarget:self andPhase:SPTouchPhaseMoved] allObjects];

    if (touches.count == 1)
    {
        // one finger touching
        SPTouch *touch = [touches objectAtIndex:0];
        SPPoint *currentPos = [touch locationInSpace:self.parent];
        SPPoint *previousPos = [touch previousLocationInSpace:self.parent];
        // ...
    }
    else if (touches.count >= 2)
    {
        // two fingers touching
        // ...
    }
}