IOS 网络浅析－（十 NSURLSession下载简介）

之前本来打算在写两个篇幅，但是在这片开写的时候觉得还是写一个比较好，有利于理解。NSURLSession下载是通过NSURLSession下载代理实现的，上一片也介绍了代理，之所以没有介绍下载是因为，我个人觉得容易混淆（应该是我太笨）。这篇随笔里将会介绍NSURLSession下载的实现，包括下载的开始，挂起，继续。希望本片可以给大家带来点点收获。下一篇我打算介绍一下AFN毕竟实际开发中AFN才是硬道理。

 

////  ViewController.m//  NSURLSession大文件下载////  Created by 大欢 on 16/3/21.//  Copyright © 2016年 大欢. All rights reserved.//#import "ViewController.h"@interface ViewController ()<NSURLSessionDownloadDelegate>@property (nonatomic, strong) NSURLSessionDownloadTask * task;@property (nonatomic, strong) NSData * resumeData;@property (nonatomic, strong) NSURLSession * session;@end@implementation ViewController- (IBAction)start:(id)sender {        NSURLSession * session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[[NSOperationQueue alloc] init]];        self.session = session;    self.task = [session downloadTaskWithURL:[NSURL URLWithString:[@"http://192.168.1.200/DOM解析.mp4"stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]]];        [self.task resume];}- (IBAction)pause:(id)sender {        //暂停就是将任务挂起        [self.task cancelByProducingResumeData:^(NSData * _Nullable resumeData) {                //保存已下载的数据        self.resumeData = resumeData;    }];}- (IBAction)resume:(id)sender {        //可以使用ResumeData创建任务        self.task = [self.session downloadTaskWithResumeData:self.resumeData];        //开启继续下载    [self.task resume];    }- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view, typically from a nib.        NSLog(@"%@",NSSearchPathForDirectoriesInDomains(9, 1, 1));}/*   监测临时文件下载的数据大小，当每次写入临时文件时，就会调用一次  bytesWritten 单次写入多少 totalBytesWritten  已经写入了多少 totalBytesExpectedToWrite 文件总大小  */- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask      didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWrittentotalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite {        //打印下载百分比    NSLog(@"%f",totalBytesWritten * 1.0 / totalBytesExpectedToWrite);    }//下载完成- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTaskdidFinishDownloadingToURL:(NSURL *)location {            NSString * cachesPath = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:downloadTask.response.suggestedFilename];        NSFileManager * mgr = [NSFileManager defaultManager];        [mgr moveItemAtURL:location toURL:[NSURL fileURLWithPath:cachesPath] error:NULL];    }- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error {        NSLog(@"%@",error);}- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}@end