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()
}
}
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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。