Object jumps back to its initial position every time toughesBegan is triggered

Question

I am writing a simple move object program. I'm expecting my object to move towards my touch position. Everything works fine except that the object position gets reset to its initial position every time I touchesBegan is triggered.

Could someone please explain the order in which methods run when an event is triggered?

- (void)viewDidLoad
{
   planeSpeed = 0;
   timeStep = 200;

   planeCenterX = plane.center.x;
   planeCenterY = plane.center.y;

   timer = [NSTimer scheduledTimerWithTimeInterval:(double)timeStep/1000 target:self selector:@selector(moveAirplane) userInfo:nil repeats:YES];
}

-(void) moveAirplane
{
    speedX = planeSpeed * cos(planeVelocutyAngle);
    speedY = planeSpeed * sin(planeVelocutyAngle);

    planeCenterX = planeCenterX + (int) speedX;
    planeCenterY = planeCenterY + (int) speedY;

    plane.center = CGPointMake(planeCenterX, planeCenterY);
    plane.transform = CGAffineTransformMakeRotation(planeVelocutyAngle);
}

-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
   UITouch * touch = [touches anyObject];
   CGPoint touchPoint = [touch locationInView:self.view];

   double xDiff = (touchPoint.x - planeCenterX);
   double yDiff = (touchPoint.y - planeCenterY);

   planeVelocutyAngle = atan2(yDiff, xDiff);   // gets direction in which plane should move
   planeSpeed = 10;

}

note: it's my first iphone program!

Answer 1

I know the problem is from the rotation method:

   plane.transform = CGAffineTransformMakeRotation(planeVelocutyAngle);

I had the same problem and the only way I could solve it was by getting rid of that function.