旧的swift代码无法正常工作（动画UIView）

Question

i have found this code which is responsible for animating a UIView but unfortunately the code does not work and i can not figure the reason (maybe an older version of swift)

this is the code :

(this is helper function according to the creator)

func moveView(#view:UIView, toPoint destination:CGPoint, completion☹()->())?) {
 //Always animate on main thread
 dispatch_async(dispatch_get_main_queue(), { () Void in 
   //Use UIView animation API
   UIView.animateWithDuration(1.0, delay: 0.0, usingSpringWithDamping:    
    0.6, initialSpringVelocity: 0.3, options:          
    UIViewAnimationOptions.AllowAnimatedContent, animations: { () -> 
    Void in 
           //do actual move
           view.center = destination
    }, completion: { (complete) -> Void in
           //when animation completes, activate block if not nil
           if complete {
              if let c = completion {
                 c()
              }
           }
    })
 })
}

and this is the animation

//Create your face object (Just a UIImageView with a face as the image
var face = Face();
face.frame = CGRect(x: 0, y: 0, width: 50, height: 50)
//find our trajectory points
var center = CGPointMake(self.view.frame.size.width/2, self.view.frame.size.height/2);
var left = CGPointMake(center.x *-0.3, center.y)
var right = CGPointMake(center.x *2.2, center.y)
//place our view off screen
face.center = right
self.view.addSubview(face)
//move to center
moveView(view: face, toPoint: center) { () -> () in
  //Do your Pop
  face.pop()
  // Move to left
  moveView(view: face, toPoint: left, completion: { () -> () in
  }
}

and i quote from the creator of the code

General Steps: Create a new face on the right edge of the screen. Make the face visible. Move the face to the middle of the screen. Pop the face Start the process with the next face. Move the first face to the left as soon as the new face gets to the middle.

Actual slide animation Once again, we will do the following here: Move view off screen on the right Move to center Pop Move to left

To get the repeating effect, just call this method on a timer

and a summary :

UIView's animation API is very powerful. Both the pop and movement animations use depend on this API. If you're stuck with trying to create an animation, UIView animation block is usually a good place to start.

NOTE : im a beginner in IOS development if anyone can please explain the code for me

Answer 1

Indeed this moveView method had a few issues, one being it was written for Swift 1 (but there were also some typos, faulty characters and useless operations).

Here's the fixed version:

func moveView(view view:UIView, toPoint destination: CGPoint, afterAnim: ()->()) {
 //Always animate on main thread
 dispatch_async(dispatch_get_main_queue(), { () -> Void in
   //Use UIView animation API
   UIView.animateWithDuration(1.0, delay: 0.0, usingSpringWithDamping:
    0.6, initialSpringVelocity: 0.3, options:
    UIViewAnimationOptions.AllowAnimatedContent, animations: { () -> Void in
           //do actual move
           view.center = destination
    }, completion: { (complete) -> Void in
           //if and when animation completes, callback
           if complete {
              afterAnim()
           }
    })
 })
}

You can use it like this now:

moveView(view: face, toPoint: center) {
    //Do your Pop
    face.pop()
    // Move to left
    moveView(view: face, toPoint: left) {
        // Do stuff when the move is finished
    }
}

Observe the differences between your version and mine to understand what was obsolete/wrong and how I fixed it. I'll help if you're stuck.