IOS-网络（NSURLSession）

一、NSURLSession的基本用法

 //
 //  ViewController.m
 //  NSURLSession
 //
 //  Created by ma c on 16/2/1.
 //  Copyright © 2016年 博文科技. All rights reserved.
 //

 #import "ViewController.h"

 @interface ViewController ()<NSURLSessionDownloadDelegate>

 @end

 @implementation ViewController
 /*
  任务：任何请求都是一个任务

  NSURLSessionDataTask:普通的GET、POST请求
  NSURLSessionDownloadTask:文件下载
  NSURLSessionUploadTask:文件上传

  注意：如果给下载任务设置了completionHandler这个block，也实现了下载代理方法，优先执行block

  */
 - (void)viewDidLoad {
     [super viewDidLoad];

     self.view.backgroundColor = [UIColor cyanColor];

 }

 - (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
 {
 //    [self sendGetRequest];
 //    [self sendPostRequest];
 //    [self downlaodTask1];
     [self downlaodTask2];
 }

 #pragma mark - NSURLSessionDownloadTask2
 ///下载任务（有下载进度）
 - (void)downlaodTask2
 {
     //1.创建Session对象
     NSURLSessionConfiguration *cfg = [NSURLSessionConfiguration defaultSessionConfiguration];
     NSURLSession *session = [NSURLSession sessionWithConfiguration:cfg delegate:self delegateQueue:[NSOperationQueue mainQueue]];
     //2.创建一个任务
     NSURL *url = [NSURL URLWithString:@"http://localhost:8080/MJServer/resources/videos/minion_02.mp4"];
     NSURLSessionDownloadTask *task = [session downloadTaskWithURL:url];
     //3.开始任务
     [task resume];
 }

 #pragma mark - NSURLSessionDownloadDelegate的代理方法
 ///下载完毕时调用
 - (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(NSURL *)location
 {
     NSLog(@"didFinishDownloadingToURL--->%@",location);
     //location：文件的临时路径，下载好的文件
     NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, nil) lastObject];
     NSString *file = [caches stringByAppendingPathComponent:downloadTask.response.suggestedFilename];

     //降临时文件夹，剪切或者复制到Caches文件夹
     NSFileManager *mgr = [NSFileManager defaultManager];
     [mgr moveItemAtPath:location.path toPath:file error:nil];
 }
 ///恢复下载时调用
 - (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didResumeAtOffset:(int64_t)fileOffset expectedTotalBytes:(int64_t)expectedTotalBytes
 {

 }
 ///每当写完一部分就调用（根据文件大小调用多次）
 //bytesWritten:             这次调用写了多少
 //totalBytesWritten:        累计写了多少长度到沙河中
 //totalBytesExpectedToWrite:文件的总长度
 - (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite
 {
     double progress = (double)totalBytesWritten / totalBytesExpectedToWrite;

     NSLog(@"下载进度--->%lf",progress);

 }

 #pragma mark - NSURLSessionDownloadTask1
 ///下载任务（不能看到下载进度）
 - (void)downlaodTask1
 {
     //1.创建Session对象
     NSURLSession *session = [NSURLSession sharedSession];
     //2.创建NSURL
     NSURL *url = [NSURL URLWithString:@"http://localhost:8080/MJServer/resources/videos/minion_02.mp4"];
     NSURLSessionDownloadTask *task = [session downloadTaskWithURL:url completionHandler:^(NSURL * _Nullable location, NSURLResponse * _Nullable response, NSError * _Nullable error) {
        //location：文件的临时路径，下载好的文件
         NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, nil) lastObject];
         NSString *file = [caches stringByAppendingPathComponent:response.suggestedFilename];

         //降临时文件夹，剪切或者复制到Caches文件夹
         NSFileManager *mgr = [NSFileManager defaultManager];
         [mgr moveItemAtPath:location.path toPath:file error:nil];

         //[mgr copyItemAtPath:location.path toPath:file error:nil];

     }];
     //3.开始任务
     [task resume];
 }

 #pragma mark - NSURLSessionDataTask
 ///POST请求
 - (void)sendPostRequest
 {
     //1.创建Session对象
     NSURLSession *session = [NSURLSession sharedSession];

     //2.创建NSURL
     NSURL *url = [NSURL URLWithString:@"http://localhost:8080/MJServer/login"];
     //3.创建请求
     NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
     request.HTTPMethod = @"POST";
     //4.设置请求体
     request.HTTPBody = [@"username=123&pwd=123" dataUsingEncoding:NSUTF8StringEncoding];
     //5.创建一个任务
     NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {

         NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data
                                                              options:NSJSONReadingMutableLeaves error:nil];
         NSLog(@"sendPostRequest:%@",dict);
     }];
     //6.开始任务
     [task resume];
 }

 ///GET请求
 - (void)sendGetRequest
 {
     //1.得到session对象
     NSURLSession *session = [NSURLSession sharedSession];
     //2.创建一个任务
     NSURL *url = [NSURL URLWithString:@"http://localhost:8080/MJServer/video"];
     NSURLSessionDataTask *task = [session dataTaskWithURL:url completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {

         NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data
                                                              options:NSJSONReadingMutableLeaves error:nil];
         NSLog(@"sendGetRequest:%@",dict);
     }];
     //3.开始任务
     [task resume];
 }
 @end

二、NSURLSession的断点续传

 //
 //  ViewController.m
 //  IOS_0204_NSURLSession断点续传
 //
 //  Created by ma c on 16/2/4.
 //  Copyright © 2016年 博文科技. All rights reserved.
 //

 #import "ViewController.h"

 @interface ViewController ()<NSURLSessionDownloadDelegate>

 - (IBAction)btnClick:(UIButton *)sender;
 @property (weak, nonatomic) IBOutlet UIButton *btnClick;
 @property (weak, nonatomic) IBOutlet UIProgressView *progressView;

 @property (nonatomic, strong) NSURLSessionDownloadTask *task;
 @property (nonatomic, strong) NSData *resumeData;
 @property (nonatomic, strong) NSURLSession *session;

 @end

 @implementation ViewController

 - (void)viewDidLoad {
     [super viewDidLoad];

     self.progressView.progress = 0.01;
 }

 - (NSURLSession *)session
 {
     if (!_session) {
         //获得session
         NSURLSessionConfiguration *cfg = [NSURLSessionConfiguration defaultSessionConfiguration];
         _session = [NSURLSession sessionWithConfiguration:cfg delegate:self delegateQueue:[NSOperationQueue mainQueue]];
     }
     return _session;
 }

 - (IBAction)btnClick:(UIButton *)sender {
     //取反
     sender.selected = !sender.isSelected;

     if (sender.selected) { //开始、恢复下载

         if (self.resumeData) { //恢复下载
             [self resume];

         } else {  //开始下砸
             [self start];
         }

     } else { //暂停下载
         [self pause];
     }
 }
 //从零开始下载
 - (void)start
 {
     //1.创建一个下载任务
     NSURL *url = [NSURL URLWithString:@"http://localhost:8080/MJServer/resources/videos/minion_01.mp4"];
     self.task = [self.session downloadTaskWithURL:url];
     //2.开始任务
     [self.task resume];
 }
 //继续下载
 - (void)resume
 {
     //传入上次暂停下载返回的数据，就可以恢复下载
     self.task = [self.session downloadTaskWithResumeData:self.resumeData];

     [self.task resume];
 }
 //暂停下载
 - (void)pause
 {
     __weak typeof(self) vc = self;
     [self.task cancelByProducingResumeData:^(NSData * _Nullable resumeData) {

         //resumeData:包含了下载的开始位置
         vc.resumeData = resumeData;
         vc.task = nil;

     }];
 }
 #pragma mark - NSURLSessionDownloadDelegate的代理方法
 - (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(NSURL *)location
 {
     self.btnClick.selected = !self.btnClick.isSelected;

     NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
     //suggestedFilename建议使用的文件名，一般与服务器端的文件名一致
     NSString *file = [caches stringByAppendingPathComponent:downloadTask.response.suggestedFilename];
     //NSLog(@"%@",file);
     NSFileManager *mgr = [NSFileManager defaultManager];
     //将临时文件复制或者剪切到caches文件夹
     [mgr moveItemAtPath:location.path toPath:file error:nil];

 }

 - (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didResumeAtOffset:(int64_t)fileOffset expectedTotalBytes:(int64_t)expectedTotalBytes
 {

 }

 - (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite
 {
     //获得下载进度
     self.progressView.progress = (double)totalBytesWritten / totalBytesExpectedToWrite;
 }
 @end