iOS 边下边播的实现代码

项目中之前使用的是avplayer直接播放url地址，但是不知道是相机的wifi不够稳定还是代码的问题，app总是出现缓冲卡顿，就考虑改写成边下边播的模式，查过了许多资料，发现大部分都是用的同一种方法

avassetresourceloaderdelegate 代理方法，来看看如何实现

首先要实现两个必须的代理方法

avassetresourceloaderdelegateobjective-c
#pragma mark - avassetresourceloaderdelegate
//开始加载
- (bool)resourceloader:(avassetresourceloader *)resourceloader shouldwaitforloadingofrequestedresource:(avassetresourceloadingrequest *)loadingrequest {
  [self addloadingrequest:loadingrequest];
  return yes;
}
//取消加载
- (void)resourceloader:(avassetresourceloader *)resourceloader didcancelloadingrequest:(avassetresourceloadingrequest *)loadingrequest {
  [self removeloadingrequest:loadingrequest];
}
#pragma mark - avassetresourceloaderdelegate
//开始加载
- (bool)resourceloader:(avassetresourceloader *)resourceloader shouldwaitforloadingofrequestedresource:(avassetresourceloadingrequest *)loadingrequest {
  [self addloadingrequest:loadingrequest];
  return yes;
}
//取消加载
- (void)resourceloader:(avassetresourceloader *)resourceloader didcancelloadingrequest:(avassetresourceloadingrequest *)loadingrequest {
  [self removeloadingrequest:loadingrequest];
}

然后要定义一个下载类，其实就是分段下载数据的下载器

avassetresourceloaderdelegateobjective-c
- (void)start {
  nsmutableurlrequest * request = [nsmutableurlrequest requestwithurl:[self.requesturl originalschemeurl] cachepolicy:nsurlrequestreloadignoringcachedata timeoutinterval:requesttimeout];
  if (self.requestoffset > 0) {
    [request addvalue:[nsstring stringwithformat:@"bytes=%ld-%ld", self.requestoffset, self.filelength - 1] forhttpheaderfield:@"range"];
  }
  self.session = [nsurlsession sessionwithconfiguration:[nsurlsessionconfiguration defaultsessionconfiguration] delegate:self delegatequeue:[nsoperationqueue mainqueue]];
  self.task = [self.session datataskwithrequest:request];
  [self.task resume];
}
#pragma mark - nsurlsessiondatadelegate
//服务器响应
- (void)urlsession:(nsurlsession *)session datatask:(nsurlsessiondatatask *)datatask didreceiveresponse:(nsurlresponse *)response completionhandler:(void (^)(nsurlsessionresponsedisposition))completionhandler {
  if (self.cancel) return;
  srqlog(@"response: %@",response);
  completionhandler(nsurlsessionresponseallow);
  nshttpurlresponse * httpresponse = (nshttpurlresponse *)response;
  nsstring * contentrange = [[httpresponse allheaderfields] objectforkey:@"content-range"];
  nsstring * filelength = [[contentrange componentsseparatedbystring:@"/"] lastobject];
  self.filelength = filelength.integervalue > 0 ? filelength.integervalue : response.expectedcontentlength;
  if (self.delegate && [self.delegate respondstoselector:@selector(requesttaskdidreceiveresponse)]) {
    [self.delegate requesttaskdidreceiveresponse];
  }
}
//服务器返回数据 可能会调用多次
- (void)urlsession:(nsurlsession *)session datatask:(nsurlsessiondatatask *)datatask didreceivedata:(nsdata *)data {
  if (self.cancel) return;
  //srqlog(@"收到响应了: %@",data);
  self.cachelength += data.length;
  if (self.delegate && [self.delegate respondstoselector:@selector(requesttaskdidupdatecache)]) {
    [self.delegate requesttaskdidupdatecache];
  }
}
//请求完成会调用该方法，请求失败则error有值
- (void)urlsession:(nsurlsession *)session task:(nsurlsessiontask *)task didcompletewitherror:(nserror *)error {
  if (self.cancel) {
    srqlog(@"下载取消");
  }else {
    if (error) {
      if (self.delegate && [self.delegate respondstoselector:@selector(requesttaskdidfailwitherror:)]) {
        [self.delegate requesttaskdidfailwitherror:error];
      }
    }else {
      //可以缓存则保存文件
      if (self.cache) {
        [filehandle cachetempfilewithfilename:[nsstring filenamewithurl:self.requesturl]];
      }
      if (self.delegate && [self.delegate respondstoselector:@selector(requesttaskdidfinishloadingwithcache:)]) {
        [self.delegate requesttaskdidfinishloadingwithcache:self.cache];
      }
    }
  }
}

- (void)start {
  nsmutableurlrequest * request = [nsmutableurlrequest requestwithurl:[self.requesturl originalschemeurl] cachepolicy:nsurlrequestreloadignoringcachedata timeoutinterval:requesttimeout];
  if (self.requestoffset > 0) {
    [request addvalue:[nsstring stringwithformat:@"bytes=%ld-%ld", self.requestoffset, self.filelength - 1] forhttpheaderfield:@"range"];
  }
  self.session = [nsurlsession sessionwithconfiguration:[nsurlsessionconfiguration defaultsessionconfiguration] delegate:self delegatequeue:[nsoperationqueue mainqueue]];
  self.task = [self.session datataskwithrequest:request];
  [self.task resume];
}
#pragma mark - nsurlsessiondatadelegate
//服务器响应
- (void)urlsession:(nsurlsession *)session datatask:(nsurlsessiondatatask *)datatask didreceiveresponse:(nsurlresponse *)response completionhandler:(void (^)(nsurlsessionresponsedisposition))completionhandler {
  if (self.cancel) return;
  srqlog(@"response: %@",response);
  completionhandler(nsurlsessionresponseallow);
  nshttpurlresponse * httpresponse = (nshttpurlresponse *)response;
  nsstring * contentrange = [[httpresponse allheaderfields] objectforkey:@"content-range"];
  nsstring * filelength = [[contentrange componentsseparatedbystring:@"/"] lastobject];
  self.filelength = filelength.integervalue > 0 ? filelength.integervalue : response.expectedcontentlength;
  if (self.delegate && [self.delegate respondstoselector:@selector(requesttaskdidreceiveresponse)]) {
    [self.delegate requesttaskdidreceiveresponse];
  }
}
//服务器返回数据 可能会调用多次
- (void)urlsession:(nsurlsession *)session datatask:(nsurlsessiondatatask *)datatask didreceivedata:(nsdata *)data {
  if (self.cancel) return;
  //srqlog(@"收到响应了: %@",data);
  self.cachelength += data.length;
  if (self.delegate && [self.delegate respondstoselector:@selector(requesttaskdidupdatecache)]) {
    [self.delegate requesttaskdidupdatecache];
  }
}
//请求完成会调用该方法，请求失败则error有值
- (void)urlsession:(nsurlsession *)session task:(nsurlsessiontask *)task didcompletewitherror:(nserror *)error {
  if (self.cancel) {
    srqlog(@"下载取消");
  }else {
    if (error) {
      if (self.delegate && [self.delegate respondstoselector:@selector(requesttaskdidfailwitherror:)]) {
        [self.delegate requesttaskdidfailwitherror:error];
      }
    }else {
      //可以缓存则保存文件
      if (self.cache) {
        [filehandle cachetempfilewithfilename:[nsstring filenamewithurl:self.requesturl]];
      }
      if (self.delegate && [self.delegate respondstoselector:@selector(requesttaskdidfinishloadingwithcache:)]) {
        [self.delegate requesttaskdidfinishloadingwithcache:self.cache];
      }
    }
  }
}

最后将拿到的数据塞进avassetresourceloaderdelegate代理中，交还给avplayer，就可以播放了

avassetresourceloaderdelegateobjective-c
- (bool)finishloadingwithloadingrequest:(avassetresourceloadingrequest *)loadingrequest {
  //填充信息
  cfstringref contenttype = uttypecreatepreferredidentifierfortag(kuttagclassmimetype, (__bridge cfstringref)(mimetype), null);
  loadingrequest.contentinformationrequest.contenttype = cfbridgingrelease(contenttype);
  loadingrequest.contentinformationrequest.byterangeaccesssupported = yes;
  loadingrequest.contentinformationrequest.contentlength = self.requesttask.filelength;
  //读文件，填充数据
  nsuinteger cachelength = self.requesttask.cachelength;
  nsuinteger requestedoffset = loadingrequest.datarequest.requestedoffset;
  if (loadingrequest.datarequest.currentoffset != 0) {
    requestedoffset = loadingrequest.datarequest.currentoffset;
  }
  nsuinteger canreadlength = cachelength - (requestedoffset - self.requesttask.requestoffset);
  nsuinteger respondlength = min(canreadlength, loadingrequest.datarequest.requestedlength);
  //srqlog(@"好不容易填充一次");
  [loadingrequest.datarequest respondwithdata:[filehandle readtempfiledatawithoffset:requestedoffset - self.requesttask.requestoffset length:respondlength]];
  //如果完全响应了所需要的数据，则完成
  nsuinteger nowendoffset = requestedoffset + canreadlength;
  nsuinteger reqendoffset = loadingrequest.datarequest.requestedoffset + loadingrequest.datarequest.requestedlength;
  if (nowendoffset >= reqendoffset) {
    [loadingrequest finishloading];
    return yes;
  }
  return no;
}
- (void)player{
    self.resouerloader     = [[resourceloader alloc] init];
    self.asset = [avurlasset urlassetwithurl:[self.videourl customschemeurl] options:nil];
    [self.asset.resourceloader setdelegate:self.resouerloader queue:dispatch_get_main_queue()];
    _playeritem = [avplayeritem playeritemwithasset:self.asset];
    _players = [avplayer playerwithplayeritem:_playeritem];
}

- (bool)finishloadingwithloadingrequest:(avassetresourceloadingrequest *)loadingrequest {
  //填充信息
  cfstringref contenttype = uttypecreatepreferredidentifierfortag(kuttagclassmimetype, (__bridge cfstringref)(mimetype), null);
  loadingrequest.contentinformationrequest.contenttype = cfbridgingrelease(contenttype);
  loadingrequest.contentinformationrequest.byterangeaccesssupported = yes;
  loadingrequest.contentinformationrequest.contentlength = self.requesttask.filelength;
  //读文件，填充数据
  nsuinteger cachelength = self.requesttask.cachelength;
  nsuinteger requestedoffset = loadingrequest.datarequest.requestedoffset;
  if (loadingrequest.datarequest.currentoffset != 0) {
    requestedoffset = loadingrequest.datarequest.currentoffset;
  }
  nsuinteger canreadlength = cachelength - (requestedoffset - self.requesttask.requestoffset);
  nsuinteger respondlength = min(canreadlength, loadingrequest.datarequest.requestedlength);
  //srqlog(@"好不容易填充一次");
  [loadingrequest.datarequest respondwithdata:[filehandle readtempfiledatawithoffset:requestedoffset - self.requesttask.requestoffset length:respondlength]];
  //如果完全响应了所需要的数据，则完成
  nsuinteger nowendoffset = requestedoffset + canreadlength;
  nsuinteger reqendoffset = loadingrequest.datarequest.requestedoffset + loadingrequest.datarequest.requestedlength;
  if (nowendoffset >= reqendoffset) {
    [loadingrequest finishloading];
    return yes;
  }
  return no;
}
- (void)player{
    self.resouerloader     = [[resourceloader alloc] init];
    self.asset = [avurlasset urlassetwithurl:[self.videourl customschemeurl] options:nil];
    [self.asset.resourceloader setdelegate:self.resouerloader queue:dispatch_get_main_queue()];
    _playeritem = [avplayeritem playeritemwithasset:self.asset];
    _players = [avplayer playerwithplayeritem:_playeritem];
}

注意：此方法服务器端最好支持range头，这样才是分段下载。

总结

以上所述是小编给大家介绍的ios 边下边播的实现代码，希望对大家有所帮助