Applying an impulse to bullets - swift

Question

I have player (SKSpriteNode) he can move and rotate, and I want to shoot five bullets from him, but with another angle. I use this code:
let sinus = sin(player.zRotation)
let cosinus = cos(player.zRotation)
bullet.physicsBody!.applyImpulse(CGVector(dx: -sinus * 100, dy: cosinus * 100))
But, i do not know how to correctly set the vector with angle. I try to make something like this:
Can anyone help me please!

Answer 1

According with this diagram:
you must change the zRotation of your bullets.
Remember that zRotation is expressed in radians so if you need:
extension CGFloat {
var radiansToDegrees: CGFloat {
return self * CGFloat(180.0 / M_PI)
}
var degreesToRadians: CGFloat {
return self * CGFloat(M_PI / 180.0)
}
}
To rotate your bullets you can also use (also this one is expressed in radians) :
let rotate = SKAction.rotateByAngle(angle, duration: 0.01)
You can calculate also the speed and the angle of your bullet impulses :
extension CGVector {
func speed() -> CGFloat {
return sqrt(dx*dx+dy*dy)
}
func angle() -> CGFloat {
return atan2(dy, dx)
}
}
If you need you can connect these element with the screen touches as explained in detail here
About your comments you can use this formula (already explained in my link):
let angle = atan2(location.y - cannon.position.y , location.x - cannon.position.x)
cannon.zRotation = angle - CGFloat(M_PI_2)