你的位置:首页 > 操作系统

[操作系统]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