前言
简单实现弹幕功能，表跟我谈效率，但也有用队列控制同时弹的数量。
正文
代码实现：
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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<Array<Danmaku>>(count: 3, repeatedValue: Array<Danmaku>()) 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 < 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() } } |
代码说明：
代码控制了最多同时只能弹三行，每行最后一条如果延迟大于跑弹幕的时间（已经有一条处于完全等待状态）就自动切到下一行，超过最大限制就等待。
* rowArray 主要用于查询前一个弹幕的位置和时间
* 别忘了在 deinit 里面加上 danmakuQueue.cancelAllOperations()
* 注意 NSBlockOperation 的 block 并不在主线程上
以上就是对IOS开发 简单的弹幕功能的实现代码，有需要开发这种功能的朋友可以参考下。
