做网站发违规内容 网警抓不抓,全国十大装饰公司排行,承德网站建设价格,网站 平台建设情况介绍在视频的需求中#xff0c;遇到这样一个需求#xff0c;播放一视频的时候#xff0c;要预下载 后面10条视频#xff0c;但是只下载后面十条视频的前面1M
实现方法 1 创建请求时设置cacheLength resource [[IdiotResource alloc] init];resource.requestURL task.request…在视频的需求中遇到这样一个需求播放一视频的时候要预下载 后面10条视频但是只下载后面十条视频的前面1M
实现方法 1 创建请求时设置cacheLength resource [[IdiotResource alloc] init];resource.requestURL task.requestURL;resource.requestOffset task.requestOffset;resource.fileLength task.fileLength;resource.cachePath task.cachePath;//预先下载1Mresource.cacheLength 1024 * 1024;resource.resourceType IdiotResourceTypeNet;//网络资源[self.resources addObject:resource];二 创建请求时设置 请求头的Range
- (void)fetchFromNetwork:(IdiotResource *)task withResource:(IdiotResource *)resource{NSMutableURLRequest * request [NSMutableURLRequest requestWithURL:[resource.requestURL originalSchemeURL] cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:10];if (resource.cacheLength 0) {[request addValue:[NSString stringWithFormat:bytes%lld-%lld, MAX(resource.requestOffset, task.requestOffset task.cacheLength), resource.requestOffsetresource.cacheLength-1] forHTTPHeaderField:Range];}else{[request addValue:[NSString stringWithFormat:bytes%lld-, resource.requestOffset] forHTTPHeaderField:Range];}NSURLSessionDataTask * datatask [self.session dataTaskWithRequest:request];datatask.taskDescription [NSString stringWithFormat:%lld,task.requestOffset];[datatask resume];self.currentDataTask datatask;
}三 如何获取完整文件的大小
在 - (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition))completionHandler { 代理方法里面 通过获取响应头的 Content-Range 字段来获取注意不能通过 Content-Length来获取因为这个时候Content-Length 是我们设置的请求部分的大小不是完整的大小
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition))completionHandler {IdiotResource * task [self.taskDic objectForKey:dataTask.taskDescription];if (task.cancel) return;if (task.fileLength 0) {NSHTTPURLResponse * httpResponse (NSHTTPURLResponse *)response;NSString * contentRange [[httpResponse allHeaderFields] objectForKey:Content-Range];NSString * fileLength [[contentRange componentsSeparatedByString:/] lastObject];task.fileLength fileLength.integerValue 0 ? fileLength.integerValue : response.expectedContentLength;}if (self.currentResource.fileLength 0) {self.currentResource.fileLength task.fileLength;}if (!task.cachePath.length) {task.cachePath [IdiotFileManager createSliceWithUrl:task.requestURL sliceName:[NSString stringWithFormat:%lld-%lld,task.requestOffset,task.fileLength]];}if (self.currentResource.cacheLength 0) {self.currentResource.cacheLength task.fileLength - task.requestOffset;}completionHandler(NSURLSessionResponseAllow);
}如下图所示
