#import "ViewController.h"@interface ViewController ()<NSURLSessionDataDelegate>@property (weak, nonatomic) IBOutlet UIProgressView *proessView;/** 接受响应体信息 */@property (nonatomic, strong) NSFileHandle *handle;@property (nonatomic, assign) NSInteger totalSize;@property (nonatomic, assign) NSInteger currentSize;@property (nonatomic, strong) NSString *fullPath;@end@implementation ViewController-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{    //1.url    NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/resources/videos/minion_02.mp4"];        //2.创建请求对象    NSURLRequest *request = [NSURLRequest requestWithURL:url];        //3.创建会话对象,设置代理    /*     第一个参数:配置信息 [NSURLSessionConfiguration defaultSessionConfiguration]     第二个参数:代理     第三个参数:设置代理方法在哪个线程中调用     */    NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[NSOperationQueue mainQueue]];        //4.创建Task    NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request];        //5.执行Task    [dataTask resume];}#pragma mark ----------------------#pragma mark NSURLSessionDataDelegate/** *  1.接收到服务器的响应 它默认会取消该请求 * *  @param session           会话对象 *  @param dataTask          请求任务 *  @param response          响应头信息 *  @param completionHandler 回调 传给系统 */-(void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition))completionHandler{    //获得文件的总大小    self.totalSize = response.expectedContentLength;        //获得文件全路径    self.fullPath = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:response.suggestedFilename];        //创建空的文件    [[NSFileManager defaultManager]createFileAtPath:self.fullPath contents:nil attributes:nil];        //创建文件句柄    self.handle = [NSFileHandle fileHandleForWritingAtPath:self.fullPath];        [self.handle seekToEndOfFile];    /*     NSURLSessionResponseCancel = 0,取消 默认     NSURLSessionResponseAllow = 1, 接收     NSURLSessionResponseBecomeDownload = 2, 变成下载任务     NSURLSessionResponseBecomeStream        变成流     */    completionHandler(NSURLSessionResponseAllow);}/** *  接收到服务器返回的数据 调用多次 * *  @param session           会话对象 *  @param dataTask          请求任务 *  @param data              本次下载的数据 */-(void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data{        //写入数据到文件    [self.handle writeData:data];        //计算文件的下载进度    self.currentSize += data.length;    NSLog(@"%f",1.0 * self.currentSize / self.totalSize);        self.proessView.progress = 1.0 * self.currentSize / self.totalSize;}/** *  请求结束或者是失败的时候调用 * *  @param session           会话对象 *  @param dataTask          请求任务 *  @param error             错误信息 */-(void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error{    NSLog(@"%@",self.fullPath);        //关闭文件句柄    [self.handle closeFile];    self.handle = nil;}@end