Swift 2: Method for giving all sprites spawned a change in velocity
<p>I am spawning a new sprite every 4 second with a NSTimer. This is the sprite code:</p>

<pre><code>    enemy1 = SKSpriteNode(texture: enemyTexture)
    enemy1.position = CGPoint(x: CGRectGetMidX(self.frame) - 300, y: CGRectGetMidY(self.frame) - 300)
    enemy1.physicsBody = SKPhysicsBody(texture: enemyTexture, size: enemyTexture.size())
    enemy1.physicsBody!.affectedByGravity = false
    enemy1.physicsBody!.allowsRotation = false
    enemy1.setScale(0.4)
    self.addChild(enemy1)
</code></pre>

<p>I am looking for a method to give all the enemy1 sprite a velocity like this whenever i want to:</p>

<pre><code>   enemy1.physicsBody!.velocity = CGVectorMake(70, 0)
</code></pre>

<p>I want the velocity to stay the same until i decide to change it and i do that by adding the code in the update function. </p>

<p>So my question is how can i give a constant velocity to all spawned sprites?</p>