导语

• 现在NSURLConnection在开发中会使用的越来越少，iOS9已经将NSURLConnection废弃，现在最低版本一般适配iOS7，所以也可以使用。

• NSURLConnection相对于NSURLSession,安全性低。NSURLConnection下载有峰值，比较麻烦处理。
• 尽管适配最低版本iOS7，也可以使用NSURLSession。AFN已经不支持NSURLConnection。
•  NSURLSession：默认是挂起状态，如果要请求网络，需要开启。

     [NSURLSession sharedSession] 获取全局的NSURLSession对象。在iPhone的所有app共用一个全局session.

     NSURLSessionUploadTask -> NSURLSessionDataTask -> NSURLSessionTask

     NSURLSessionDownloadTask -> NSURLSessionTask

     NSURLSessionDownloadTask下载，默认下载到tmp文件夹。下载完成后删除临时文件。所以我们要在删除文件之前，将它移动到Cache里。

NSURLSession详解

1. NSURLSession基础

2. NSURLSession代理
3. NSURLSession大文件下载
4. NSURLSession断点续传

1.NSURLSession基础

• 第一种网络请求方法  

//创建URL    NSURL * url = [NSURL URLWithString:@"http://192.168.1.200/login.php?username=haha&password=123"];    //创建请求    //    NSURLRequest * request = [NSURLRequest requestWithURL:url];    //创建Session    NSURLSession * session = [NSURLSession sharedSession];    //创建任务    NSURLSessionDataTask * task = [session dataTaskWithURL:url completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {        NSLog(@"%@",[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);    }];    //开启网络任务    [task resume];

• 第二种网络请求方法

//创建URL    NSURL * url = [NSURL URLWithString:@"http://192.168.1.200/login.php?username=haha&password=123"];    //创建请求    NSURLRequest * request = [NSURLRequest requestWithURL:url];    //创建Session    NSURLSession * session = [NSURLSession sharedSession];    //创建任务    NSURLSessionDataTask * task = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {        NSLog(@"%@",[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);            }];    //开启网络任务    [task resume];

• POST请求

NSURL * url = [NSURL URLWithString:@"http://192.168.1.200/login.php"];        NSMutableURLRequest * request = [NSMutableURLRequest requestWithURL:url];        //设置请求方法    request.HTTPMethod = @"POST";        //设置请求体    request.HTTPBody = [@"username=haha&password=123" dataUsingEncoding:NSUTF8StringEncoding];        [[[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {                NSLog(@"%@",[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);            }] resume];

• 下载文件

NSURL * url = [NSURL URLWithString:[@"http://192.168.1.200/DOM解析.mp4" stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];        NSURLSession * session = [NSURLSession sharedSession];    NSURLSessionDownloadTask * downloadTask = [session downloadTaskWithURL:url completionHandler:^(NSURL * _Nullable location, NSURLResponse * _Nullable response, NSError * _Nullable error) {                //location 下载到沙盒的地址        NSLog(@"下载完成%@",location);            //response.suggestedFilename 响应信息中的资源文件名        NSString * cachesPath = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:response.suggestedFilename];                NSLog(@"缓存地址%@",cachesPath);                //获取文件管理器        NSFileManager * mgr = [NSFileManager defaultManager];        //将临时文件移动到缓存目录下        //[NSURL fileURLWithPath:cachesPath] 将本地路径转化为URL类型        //URL如果地址不正确，生成的url对象为空                [mgr moveItemAtURL:location toURL:[NSURL fileURLWithPath:cachesPath] error:NULL];            }];        [downloadTask resume];

2.NSURLSession代理

 

- (void)touchesBegan:(NSSet
     
       *)touches withEvent:(UIEvent *)event {         //  全局session    //    NSURLSession * session = [NSURLSession sharedSession];    //创建自定义session    //NSURLSessionConfiguration 的 配置    //[[NSOperationQueue alloc] init] 也可以写成 nil    NSURL * url = [NSURL URLWithString:@"http://192.168.1.200/login.php?username=haha&password=123"];        NSURLSession * session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[[NSOperationQueue alloc] init]];        NSURLSessionDataTask * task = [session dataTaskWithURL:url];        [task resume];    }//接收到服务器响应- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTaskdidReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition disposition))completionHandler {        NSLog(@"%s",__FUNCTION__);        //允许接受服务器回传数据    completionHandler(NSURLSessionResponseAllow);}//接收服务器回传的数据,有可能执行多次- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask    didReceiveData:(NSData *)data {        NSLog(@"%@",[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);}//请求成功或失败- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error {        NSLog(@"%@",error);}
     

 

3.NSURLSession大文件下载

 

#import "ViewController.h"@interface ViewController ()
     
      @end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view, typically from a nib.        NSLog(@"%@",NSSearchPathForDirectoriesInDomains(9, 1, 1));}- (void)touchesBegan:(NSSet
      
        *)touches withEvent:(UIEvent *)event {        NSURLSession * session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[[NSOperationQueue alloc] init]];        NSURLSessionDownloadTask * task = [session downloadTaskWithURL:[NSURL URLWithString:[@"http://192.168.1.200/DOM解析.mp4"stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]]];        [task resume];}/*   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);}
      
     

 

4.NSURLSession断点续传

 

#import "ViewController.h"@interface ViewController ()
     
      @property (nonatomic, strong) NSURLSessionDownloadTask * task;@property (nonatomic, strong) NSData * resumeData;@property (nonatomic, strong) NSURLSession * session;@end@implementation ViewController//故事板中开始按钮的响应方法- (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://192.168.1.68/丁香花.mp3"stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]]];        [self.task resume];}//故事板中暂停按钮的响应方法- (IBAction)pause:(id)sender {        //暂停就是将任务挂起        [self.task cancelByProducingResumeData:^(NSData *resumeData) {        //保存已下载的数据        self.resumeData = resumeData;    }];}//继续按钮的响应方法- (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);}