UpdateOverrideStep2.swift

override func update(currentTime: CFTimeInterval) {
    /* Called before each frame is rendered */
    
    if lastUpdateTime == 0.0 {
        delta = 0
    } else {
        delta = currentTime - lastUpdateTime
    }

    lastUpdateTime = currentTime
    
    if fireWeapon
    {
        self.fireProjectile(CGFloat(delta))
    }
}