IOS 实现简单的弹幕功能

 let DANMAKU_SPEED: CGFloat = 150 // 弹幕每秒移动速度 let DANMAKU_SPACE_TIME: NSTimeInterval = 1 // 弹幕之间的时间间隔 let DANMAKU_MAX_ROW = 3 // 最多同时弹幕行数 let danmakuFont = UIFont.systemFontOfSize(18) // 弹幕字体大小 var rowArray = Array>(count: 3, repeatedValue: Array()) var danmakuQueue = NSOperationQueue() // 队列 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 { //检测放第几行 for var row = 0; row = 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() } }