draw line using finger and an object will follow that path? - iphone

Question

I m new to game devloping in ios. Now I want made a game similar like "Control Air Flight" and "Air Traffic Controller" ,
where a user can draw line using their finger and an object will
follow that path
so ,anyone can guide me which is best for developing like this.Can Cocos2d is best for it? Or any thing else i have to use for this.
Also If anyone knows of a tutorial already out there or any reference link please suggest me.
Thanks in Advance.

Answer 1

To simply let the object follow your finger, implement touches (and just one of its methods):
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
UITouch *touch = [touches anyObject];
CGPoint toPoint = [touch locationInView:self.view];
[yourObjectOutlet setCenter:toPoint];
}
Here, your object's center will follow your path, but you can adjust its anchor point by editing "toPoint" accordingly to object's frame.
EDIT
If you want to draw the path, then make the object follow that path, do like this:
//define an NSMutableArray in your header file (do not forget to alloc and init it in viewDidLoad), then:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
//you begin a new path, clear the array
[yourPathArray removeAllObjects];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
UITouch *touch = [touches anyObject];
CGPoint toPoint = [touch locationInView:self.view];
//now, save each point in order to make the path
[yourPathArray addObject:[NSValue valueWithCGPoint:toPoint]];
}
Now you want to start the move:
- (IBAction)startMoving{
[self goToPointWithIndex:[NSNumber numberWithInt:0]];
}
- (void)goToPointWithIndex:(NSNumber)indexer{
int toIndex = [indexer intValue];
//extract the value from array
CGPoint toPoint = [(NSValue *)[yourPathArray objectAtIndex:toIndex] CGPointValue];
//you will repeat this method so make sure you do not get out of array's bounds
if(indexer < yourPathArray.count){
[yourObject setCenter:toPoint];
toIndex++;
//repeat the method with a new index
//this method will stop repeating as soon as this "if" gets FALSE
[self performSelector:#selector(goToPointWithIndex:) with object:[NSNumber numberWithInt:toIndex] afterDelay:0.2];
}
}
That's all!