applyImpulse towards CGPoint SpriteKit - sprite-kit

Question

I'm kind of a newb in SpriteKit, game dev, as a matter of fact I'm just learning. So I got to a point where I what to move a bunch of nodes towards a users tap location. So far I fought that I might calculate a virtual right triangle and get sin and cos of angles based on the sides. Unfortunately that left me with a very strong impulse that doesn't really consider the user tap location.
Any ideas?
Thanks in advance.

Answer 1

Look up the shooting projectiles section in the tutorial by Ray Wenderlich here:
http://www.raywenderlich.com/42699/spritekit-tutorial-for-beginners
Change the code from the tutorial as follows:
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
// 1 - Choose one of the touches to work with
UITouch * touch = [touches anyObject];
CGPoint location = [touch locationInNode:self];
// 2 - Set up initial location of projectile
SKSpriteNode * projectile = [self childNodeWithName:#"desirednode"];
//make projectile point to your desired node.
// 3- Determine offset of location to projectile
CGPoint offset = rwSub(location, projectile.position);
// 4 - Bail out if you are shooting down or backwards. You can ignore this if required.
if (offset.x <= 0) return;
// 5 - OK to add now - we've double checked position
[self addChild:projectile];
// 6 - Get the direction of where to shoot
CGPoint direction = rwNormalize(offset);
// 7 - Make it shoot far enough to be guaranteed off screen
float forceValue = 200; //Edit this value to get the desired force.
CGPoint shootAmount = rwMult(direction, forceValue);
//8 - Convert the point to a vector
CGVector impulseVector = CGVectorMake(shootAmount.x, shootAmount.y);
//This vector is the impulse you are looking for.
//9 - Apply impulse to node.
[projectile.physicsBody applyImpulse:impulseVector];
}
The projectile object in the code represents your node. Also, you will need to edit the forceValue to get the desired impulse.