IOS implements a simple barrage function

preface

Simply implement the bullet screen function, table to talk to me about efficiency, but also useful for queue control of the number of simultaneous bullets.

The body of the

Code implementation:

let DANMAKU_SPEED: CGFloat = 150 //  The barrage moves every second 
 let DANMAKU_SPACE_TIME: NSTimeInterval = 1 //  The time interval between the barrage 
 let DANMAKU_MAX_ROW = 3 //  Maximum number of simultaneous barrage lines 
 let danmakuFont = UIFont.systemFontOfSize(18) //  Bullet screen font size 
 var rowArray = Array<Array<Danmaku>>(count: 3, repeatedValue: Array<Danmaku>()) 
 var danmakuQueue = NSOperationQueue() //  The 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) {
   self.msg = msg
   self.row = row
   self.delay = delay
  }
 }
 
 func queueDanmaku(msg: Msg) {
  danmakuQueue.addOperation(NSBlockOperation(block: { [weak self] in

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

  danmaku.view = label
  danmaku.size = size
  danmaku.startTime = NSDate()
  danmaku.duration = NSTimeInterval(duration)
  
  label.text = text
  label.font = danmakuFont
  label.textColor = UIColor.whiteColor()
  label.shadowColor = UIColor.blackColor()
  label.shadowOffset = CGSizeMake(0, -1.0)
  
  self.view.addSubview(label)
  UIView.animateWithDuration(Double(duration), delay: danmaku.delay, options: UIViewAnimationOptions.CurveLinear, animations: { () -> Void in
    label.left = -label.width
   }) { [weak self] (Bool) -> Void in
    if !(self?.rowArray[danmaku.row].isEmpty ?? true) {
     self?.rowArray[danmaku.row].removeFirst()
    }
    label.removeFromSuperview()
  }
 }

Code description:

The code controls that only 3 lines can be played at the same time at most. If the delay at the end of each line is greater than the running time of the barrage (there is already 1 line in the fully waiting state), it will automatically cut to the next 1 line and wait if the maximum limit is exceeded.

*rowArray is mainly used to query the location and time of the first barrage

* don't forget to add danmakuQueue.cancelAllOperations () to deinit

* note that NSBlockOperation's block is not on the main thread

The above is the IOS development of a simple bullet screen function implementation code, there is a need to develop the function of friends can refer to the next.