IOS implements simple barrage function

let DANMAKU_SPEED: CGFloat = 150 // Barrage movement speed per second let DANMAKU_SPACE_TIME: NSTimeInterval = 1 // Time interval between barrage let DANMAKU_MAX_ROW = 3 // Maximum number of barrage lines at the same time let danmakuFont = (18) // Barrage font size var rowArray = Array<Array<Danmaku>>(count: 3, repeatedValue: Array<Danmaku>()) 
 var danmakuQueue = NSOperationQueue() // Queue
 class Danmaku : NSObject{
  var msg: Msg
  var view: UILabel?
  var size = CGSize(width: 0, height: 0)
  var row = 0
  var startTime: NSDate?
  var duration: NSTimeInterval = 0
  var delay: NSTimeInterval = 0
  
  init(_ msg: Msg, _ row: Int, _ delay: NSTimeInterval = 0) {
    = msg
    = row
    = delay
  }
 }
 
 func queueDanmaku(msg: Msg) {
  (NSBlockOperation(block: { [weak self] in

   if let weakself = self {
    repeat {
     //How many rows are placed     for var row = 0; row < weakself.DANMAKU_MAX_ROW; ++row {
      let rowDanmaku = [row]
      if  == 0 {
       let danmaku = Danmaku(msg, , row)
       [row].append(danmaku)
       self?.performSelectorOnMainThread("sendDanmaku:", withObject: danmaku, waitUntilDone: true)
       return
      } else {
       if let lastDanmaku =  {
        if let startTime =  {
         let now = NSDate()
         let seconds = (startTime)
         let widthDuration = Double( / weakself.DANMAKU_SPEED)
         
         var delay = seconds - weakself.DANMAKU_SPACE_TIME - widthDuration
         if delay >= 0 {
          delay = 0
         } else {
          if  >  {
           continue
          }
         }
    
         let danmaku = Danmaku(msg, , row, abs(delay) + )
         [row].append(danmaku)
         
         self?.performSelectorOnMainThread("sendDanmaku:", withObject: danmaku, waitUntilDone: true)
         return
        }
       }
      }
     }
     
     sleep(1000)
    } while self != nil
   }
   
   }))
 }
 
 func sendDanmaku(danmaku: Danmaku) {
  let text = "\(.user_name) : \()"
  let size = NSString(string: text).sizeWithAttributes([NSFontAttributeName : danmakuFont])
  let width = ().
  let top = 54 +  * (Int() + 10)
  let label = UILabel(frame: CGRectMake(width, CGFloat(top), , ))
  let duration = (width + ) / DANMAKU_SPEED

   = label
   = size
   = NSDate()
   = NSTimeInterval(duration)
  
   = text
   = danmakuFont
   = ()
   = ()
   = CGSizeMake(0, -1.0)
  
  (label)
  (Double(duration), delay: , options: , animations: { () -> Void in
     = -
   }) { [weak self] (Bool) -> Void in
    if !(self?.rowArray[].isEmpty ?? true) {
     self?.rowArray[].removeFirst()
    }
    ()
  }
 }