代码详解iOS视频直播弹幕功能

@interface barragemodel : nsobject
/** 用户昵称 */
@property(nonatomic,copy)nsstring *username;
/** 消息内容 */
@property(nonatomic,copy)nsstring *usermsg;
/** 用户头像 */
@property(nonatomic,copy)nsstring *userheadimageurl;
@end

#import <uikit/uikit.h>
@class barragemodel;
@interface barrageview : uiview
/**
 * 记录当前最后一个弹幕view，通过这个view来计算是显示在哪个弹幕轨道上
 */
@property(nonatomic,retain) uiview *lastanimateview;
/**
 * 发送弹幕
 *
 * @param msgmodel 弹幕数据model
 */
-(void)barragesendmsg:(barragemodel *)msgmodel;
@end

#import <uikit/uikit.h>
@class barragemodel;
@interface barrageview : uiview

/**
 * 记录当前最后一个弹幕view，通过这个view来计算是显示在哪个弹幕轨道上
 */
@property(nonatomic,retain) uiview *lastanimateview;
/**
 * 发送弹幕
 *
 * @param msgmodel 弹幕数据model
 */
-(void)barragesendmsg:(barragemodel *)msgmodel;
@end
在.m文件中
#import "barrageview.h"
#import "barragemodel.h"
//屏幕的尺寸
#define screen_frame  [[uiscreen mainscreen] bounds]
//屏幕的高度
#define screen_height cgrectgetheight(screen_frame)
//屏幕的宽度
#define screen_width cgrectgetwidth(screen_frame)

@interface barrageview()
{
  cgfloat _minspacetime; /** 最小间距时间 */
}
/** 数据源 */
@property (nonatomic,retain)nsmutablearray *dataarr;

/** 弹幕ui的重用池 */
@property (nonatomic,retain)nsmutablearray *resuingarr;
@end
@implementation barrageview
- (instancetype)initwithframe:(cgrect)frame
{
  self = [super initwithframe:frame];
  if (self) {
    [self setinterface];
  }
  return self;
}
-(void)setinterface
{
  //初始化弹幕数据源，以及重用池
  self.dataarr = [nsmutablearray array];
  self.resuingarr = [nsmutablearray array];
  //创建第一个弹幕加入重用池作为备用
  uiview *view = [self createui];
  [self.resuingarr addobject:view];
  //设置弹幕数据的初始轮询时间
  _minspacetime = 1;
  //检查是否可以取弹幕数据进行动画
  [self checkstartanimatiom];
}
-(void)checkstartanimatiom
{
  //当有数据信息的时候
  if (self.dataarr.count>0) {
    if (self.resuingarr.count>0) { //当重用池里面有备用的弹幕ui时
      
      //在重用池中，取出第一个弹幕ui
      uiview *view = [self.resuingarr firstobject];
      [self.resuingarr removeobject:view];
      //取出的这个弹幕ui开始动画
      [self startanimationwithview:view];
      
    }else{ //当重用池没有备用的弹幕ui时
      
      //重新创建一个弹幕ui
      uiview *view = [self createui];
      //拿着这个弹幕ui开始动画
      [self startanimationwithview:view];
    }
  }
  //延迟执行，在主线程中不能调用sleep()进行延迟执行
  //调用自身方法，构成一个无限循环，不停的轮询检查是否有弹幕数据
  dispatch_after(dispatch_time(dispatch_time_now, (int64_t)(_minspacetime * nsec_per_sec)), dispatch_get_main_queue(), ^{
    [self checkstartanimatiom];
  });
}
-(void)startanimationwithview:(uiview *)view
{
  //取出第一条数据
  barragemodel *barragemodel = [self.dataarr firstobject];
  //计算昵称的长度
  cgsize namesize = [barragemodel.username boundingrectwithsize:cgsizemake(cgfloat_max, 14) options:nsstringdrawinguseslinefragmentorigin|nsstringdrawingusesfontleading attributes:@{                                                                         } context:nil].size;
  //计算消息的长度
  cgsize msgsize = [barragemodel.usermsg boundingrectwithsize:cgsizemake(cgfloat_max, 14) options:nsstringdrawinguseslinefragmentorigin|nsstringdrawingusesfontleading attributes:@{                                                               nsfontattributename:[uifont systemfontofsize:14]
} context:nil].size; 
  uiimageview *headimageview; //头像
  uilabel *usernamelabel;   //昵称
  uilabel *usermsglabel;   //消息内容
  //进行赋值，宽度适应
  for (uiview *subview in view.subviews) {
    if (subview.tag == 1000) {
      headimageview = (uiimageview *)subview;
      headimageview.image = [uiimage imagenamed:@""];
      
    }else if (subview.tag == 1001){
      usernamelabel = (uilabel *)subview;
      usernamelabel.text = barragemodel.username;
      //重新设置名称label宽度
      cgrect namerect = usernamelabel.frame;
      namerect.size.width = namesize.width;
      usernamelabel.frame = namerect;
    }else{
      usermsglabel = (uilabel *)subview;
      usermsglabel.text = barragemodel.usermsg;
      //重新设置消息内容label宽度
      cgrect msgrect = usermsglabel.frame;
      msgrect.size.width = msgsize.width;
      usermsglabel.frame = msgrect;
    }
  }
  //重新设置弹幕的总体宽度 = 头像宽度 + 头像左右两侧距离 + (如果名字宽度大于消息内容宽度，以名字宽度为基准，如果名字宽度小于消息内容宽度，以消息内容宽度为基准)
  view.frame = cgrectmake(screen_width, 0, cgrectgetwidth(headimageview.frame) + 4 + (cgrectgetwidth(usernamelabel.frame)>cgrectgetwidth(usermsglabel.frame)?cgrectgetwidth(usernamelabel.frame):cgrectgetwidth(usermsglabel.frame)), cgrectgetheight(self.frame));
  //不管弹幕长短，速度要求一致。 v(速度) 为固定值 = 100(可根据实际自己调整)
  // s = 屏幕宽度+弹幕的宽度 v = 100(可根据实际自己调整)
  // v(速度) = s(路程)/t(时间) -------> t(时间) = s(路程)/v(速度);
  cgfloat duration = (view.frame.size.width+screen_width)/100;
  //最小间距运行时间为：弹幕从屏幕外完全移入屏幕内的时间 + 间距的时间
  _minspacetime = (view.frame.size.width + 30)/100;
  //最后做动画的view
  _lastanimateview = view;  
  //弹幕ui开始动画
  [uiview animatewithduration:duration delay:0 options:uiviewanimationoptioncurvelinear animations:^{
    //运行至左侧屏幕外
    cgrect frame = view.frame;
    view.frame = cgrectmake(-frame.size.width, 0, frame.size.width, frame.size.height);
  } completion:^(bool finished) {
    //动画结束重新回到右侧初始位置
    view.frame = cgrectmake(screen_width, 0, 0, cgrectgetheight(self.frame));
    //重新加入重用池
    [self.resuingarr addobject:view];
  }];  
  //将这个弹幕数据移除
  [self.dataarr removeobject:barragemodel];
}
#pragma mark public method
-(void)barragesendmsg:(barragemodel *)msgmodel{
  //添加弹幕数据
  [self.dataarr addobject:msgmodel];
}
#pragma mark 创建控件
-(uiview *)createui
{
  uiview *view = [[uiview alloc] initwithframe:cgrectmake(screen_width, 0, 0, cgrectgetheight(self.frame))];
  view.backgroundcolor = [uicolor colorwithwhite:0 alpha:0.3];
  uiimageview *headimageview = [[uiimageview alloc] initwithframe:cgrectmake(2, 2, cgrectgetheight(self.frame)-4, cgrectgetheight(self.frame)-4)];
  headimageview.layer.cornerradius = headimageview.frame.size.width/2;
  headimageview.layer.maskstobounds = yes;
  headimageview.tag = 1000;
  headimageview.backgroundcolor = [uicolor redcolor];
  [view addsubview:headimageview];
  uilabel *usernamelabel = [[uilabel alloc] initwithframe:cgrectmake(cgrectgetmaxx(headimageview.frame) + 2, 0, 0,14)];
  usernamelabel.font = [uifont systemfontofsize:14];
  usernamelabel.tag = 1001;
  [view addsubview:usernamelabel];
  uilabel *usermsglabel = [[uilabel alloc] initwithframe:cgrectmake(cgrectgetmaxx(headimageview.frame)+2, cgrectgetmaxy(usernamelabel.frame), 0, 14)];
  usermsglabel.font = [uifont systemfontofsize:14];
  usermsglabel.tag = 1002;
  [view addsubview:usermsglabel];
  [self addsubview:view];
  return view;
}

#import "viewcontroller.h"
#import "barrageview.h"
#import "barragemodel.h"
//屏幕的尺寸
#define screen_frame [[uiscreen mainscreen] bounds]
//屏幕的高度
#define screen_height cgrectgetheight(screen_frame)
//屏幕的宽度
#define screen_width cgrectgetwidth(screen_frame)
@interface viewcontroller ()
/** 第一个弹幕轨道 */
@property (nonatomic,retain)barrageview *barrageviewone;
/** 第二个弹幕轨道 */
@property (nonatomic,retain)barrageview *barrageviewtwo;
@end
@implementation viewcontroller
- (void)viewdidload {
 [super viewdidload];
 //创建第一个弹幕轨道
 _barrageviewone = [[barrageview alloc]initwithframe:cgrectmake(0,200, screen_width, 34)];
 [self.view addsubview:_barrageviewone];
 //创建第二个弹幕轨道
 _barrageviewtwo = [[barrageview alloc]initwithframe:cgrectmake(0,300, screen_width, 34)];
 [self.view addsubview:_barrageviewtwo];
}
-(void)touchesbegan:(nsset<uitouch *> *)touches withevent:(uievent *)event
{
 nstimer *timer = [nstimer scheduledtimerwithtimeinterval:1 target:self selector:@selector(sendmessage) userinfo:nil repeats:yes];
 [timer fire];
}
-(void)sendmessage
{
 barragemodel *model = [[barragemodel alloc]init];
 model.username = @[@"张三",@"李四",@"王五",@"赵六",@"七七",@"八八",@"九九",@"十十",@"十一",@"十二",@"十三",@"十四"][arc4random()%12];
 model.usermsg = @[@"阿达个人",@"都是vsqe12qwe",@"胜多负少的凡人歌",@"委屈翁二群二",@"12312",@"热帖柔荑花",@"发彼此彼此",@"ok泼墨",@"人体有图图",@"额外热无若无",@"微软将围"][arc4random()%11];
 //计算当前做动画的弹幕ui的位置
 cgfloat onepositon = _barrageviewone.lastanimateview.layer.presentationlayer.frame.size.width + _barrageviewone.lastanimateview.layer.presentationlayer.frame.origin.x;
 //计算当前做动画的弹幕ui的位置
 cgfloat twopositon = _barrageviewtwo.lastanimateview.layer.presentationlayer.frame.size.width + _barrageviewtwo.lastanimateview.layer.presentationlayer.frame.origin.x;
 if ( onepositon < twopositon ) {
 [_barrageviewone barragesendmsg:model];
 }else{
 [_barrageviewtwo barragesendmsg:model];
 }
}
@end