Basic Drag and Drop in iOS

Assume you have a UIView scene with a background image and many vehicles, you may define each new vehicle as a UIButton (UIImageView will probably work too):

UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
[button addTarget:self action:@selector(imageTouch:withEvent:) forControlEvents:UIControlEventTouchDown];
[button addTarget:self action:@selector(imageMoved:withEvent:) forControlEvents:UIControlEventTouchDragInside];
[button setImage:[UIImage imageNamed:@"vehicle.png"] forState:UIControlStateNormal];
[self.view addSubview:button];

Then you may move the vehicle wherever you want, by responding to the UIControlEventTouchDragInside event, e.g.:

- (IBAction) imageMoved:(id) sender withEvent:(UIEvent *) event
{
    CGPoint point = [[[event allTouches] anyObject] locationInView:self.view];
    UIControl *control = sender;
    control.center = point;
}

It’s a lot easier for individual vehicle to handle its own drags, comparing to manage the scene as a whole.