Slider determines gravity - ios

Question

So far I've created a rectangle that starts from the bottom and moves upward using UiDynamicAnimator. I would like the user to determine the "strength" of the negative gravity. I want the user to determine the value through a slider.
This is my code so far:
import UIKit
class ViewController: UIViewController {
var orangeSquare: UIView?
var animator: UIDynamicAnimator?
override func viewDidLoad() {
super.viewDidLoad()
func sliderChanged(sender: AnyObject) {
var sliderValue = sender.value
}
//Create animation
let dim = CGRectMake(100, 500, 200, 100)
orangeSquare = UIView(frame: dim)
orangeSquare?.backgroundColor = UIColor.orangeColor()
//Add item to the screen
self.view.addSubview(orangeSquare!)
//Initialize the animator
animator = UIDynamicAnimator(referenceView: self.view)
//Add gravity
let gravity = UIGravityBehavior(items: [orangeSquare!])
let direction = CGVectorMake(0.0, sliderValue)
gravity.gravityDirection = direction
//Collision
let boundries = UICollisionBehavior(items: [orangeSquare!])
boundries.translatesReferenceBoundsIntoBoundary = true
//Add animations
animator?.addBehavior(boundries)
animator?.addBehavior(gravity)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
I get two errors:
"Ambiguous use of ´value´" and
"Use of unresolved identifier ´sliderValue´"
How do I convert ´sliderValue´ into a float with just one decimal point?

Answer 1

your code is missing a few things. sliderValue is an unresolved identifier because you have only declared it within sliderChanged but are referring to it in the main body of viewDidLoad. Also, I think that your use of value is ambiguous because you have declared the parameter to the function as AnyObject, whose value could be any one of a number of things!
Your code was missing a mechanism linking a change in the value of the slider with a change in the gravity behaviour. As such, I've implemented this using an explicit target attached to the slider object. I've also thrown in a label showing the magnitude of the gravitational force. This is quite rough but I think it achieves what you were looking to do.
import UIKit
class ViewController: UIViewController {
var dynamicAnimator : UIDynamicAnimator!
var gravityBehaviour : UIGravityBehavior!
var orangeSquare : UIView!
var slider : UISlider!
var sliderLabel : UILabel!
override func viewDidLoad() {
super.viewDidLoad()
// Subviews
self.orangeSquare = {
let oS : UIView = UIView(frame: CGRect(origin: CGPoint(x: (self.view.frame.width / 2) - 100, y: 500), size: CGSize(width: 200, height: 200)))
oS.backgroundColor = UIColor.orange
return oS
}()
self.slider = UISlider(frame: CGRect(origin: CGPoint(x: 100, y: 100), size: CGSize(width: self.view.frame.width - 400, height: 50)))
self.slider.addTarget(self, action: #selector(self.sliderValueDidChange), for: UIControlEvents.allTouchEvents)
self.slider.minimumValue = -5
self.slider.maximumValue = 5
self.slider.value = 0
self.sliderLabel = UILabel(frame: CGRect(origin: CGPoint(x: self.view.frame.width - 100, y: 100), size: CGSize(width : 50, height: 50)))
self.sliderLabel.backgroundColor = UIColor.red
self.sliderLabel.textAlignment = NSTextAlignment.center
self.sliderLabel.textColor = UIColor.white
self.sliderLabel.text = String(self.slider.value)
// Assemble
self.view.addSubview(self.orangeSquare)
self.view.addSubview(self.slider)
self.view.addSubview(self.sliderLabel)
// Configure dynamic behaviours
self.dynamicAnimator = UIDynamicAnimator(referenceView: self.view)
self.gravityBehaviour = UIGravityBehavior(items: [self.orangeSquare])
self.gravityBehaviour.gravityDirection = CGVector(dx: 0, dy: 0)
// Configure boundaries
let boundaries : UICollisionBehavior = UICollisionBehavior(items: [self.orangeSquare])
boundaries.translatesReferenceBoundsIntoBoundary = true
self.dynamicAnimator.addBehavior(self.gravityBehaviour)
self.dynamicAnimator.addBehavior(boundaries)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func sliderValueDidChange() {
// When the slider value changes, update the label text and the gravity vector
self.sliderLabel.text = String((round(self.slider.value) * 10) / 10)
self.gravityBehaviour.gravityDirection = CGVector(dx: 0, dy: CGFloat(-1 * self.slider.value))
}
}
Hope that helps. All best!

Answer 2

import UIKit
class ViewController: UIViewController {
var dynamicAnimator : UIDynamicAnimator!
var gravityBehaviour : UIGravityBehavior!
var orangeSquare : UIView!
var slider : UISlider!
var sliderLabel : UILabel!
override func viewDidLoad() {
super.viewDidLoad()
// Subviews
self.orangeSquare = {
let oS : UIView = UIView(frame: CGRect(origin: CGPoint(x: (self.view.frame.width / 2) - 100, y: 500), size: CGSize(width: 200, height: 200)))
oS.backgroundColor = UIColor.orangeColor()
return oS
}()
self.slider = UISlider(frame: CGRect(origin: CGPoint(x: self.view.frame.width - 100, y: 100), size: CGSize(width: self.view.frame.width - 300, height: 150)))
self.slider.addTarget(self, action: #selector(self.sliderValueDidChange), forControlEvents: UIControlEvents.AllTouchEvents)
self.slider.minimumValue = -10
self.slider.maximumValue = 10
self.slider.value = 0
self.sliderLabel = UILabel(frame: CGRect(origin: CGPoint(x: self.view.frame.width - 100, y: 200), size: CGSize(width : 50, height: 50)))
self.sliderLabel.backgroundColor = UIColor.redColor()
self.sliderLabel.textAlignment = NSTextAlignment.Center
self.sliderLabel.textColor = UIColor.whiteColor()
self.sliderLabel.text = String(self.slider.value)
// Assemble
self.view.addSubview(self.orangeSquare)
self.view.addSubview(self.slider)
self.view.addSubview(self.sliderLabel)
// Configure dynamic behaviours
self.dynamicAnimator = UIDynamicAnimator(referenceView: self.view)
self.gravityBehaviour = UIGravityBehavior(items: [self.orangeSquare])
self.gravityBehaviour.gravityDirection = CGVector(dx: 0.0, dy: 0.0)
// Configure boundaries
let boundaries : UICollisionBehavior = UICollisionBehavior(items: [self.orangeSquare])
boundaries.translatesReferenceBoundsIntoBoundary = true
self.dynamicAnimator.addBehavior(self.gravityBehaviour)
self.dynamicAnimator.addBehavior(boundaries)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func sliderValueDidChange() {
// When the slider value changes, update the label text and the gravity vector
self.sliderLabel.text = String((round(self.slider.value) * 10) / 10)
self.gravityBehaviour.gravityDirection = CGVector(dx: 0, dy: CGFloat(-1 * self.slider.value))
}
}