iOS网络编程(六) NSURLSession详解

      昨夜浏览Demo的时候,看到别人请求网络数据用的是NSURLSession,当时就在想这里什么,怎么没有用过,引起了我的好奇心,遂去百度-谷歌-官方文档一一查看,有了一定的了解,原来NSURLSession是iOS7中新的网络接口，它与咱们熟悉的NSURLConnection是并列的。

      查找资料,写了一个小Demo,大家可以看看,有什么不足的地方,可以留言帮我指出来.

//
//  HMTRootViewController.m
//
//
//  Created by HMT on 14-6-7.
//  Copyright (c) 2014年 胡明涛. All rights reserved.
//

#import "HMTRootViewController.h"
#import "HMTAppDelegate.h"

@interface HMTRootViewController ()

@property (nonatomic,strong)UIImageView *imageView;
@property (nonatomic,strong)UIProgressView *progressIndicator;

@property (nonatomic,strong)NSURLSession *urlSession;         //  普通会话
//@property (nonatomic,strong)NSURLSession *backgroundSession;  //  后台会话
@property (nonatomic,strong)NSURLSessionDownloadTask *sessionDownloadTask;  //  下载Task
@property (nonatomic,strong)NSURLSessionDownloadTask *resumableTask;        //  恢复下载Task
@property (nonatomic,strong)NSURLSessionDownloadTask *backgroundTask;       //  后台下载Task
@property (nonatomic,strong)NSData *partialData;   //  下载的局部数据

@end

@implementation HMTRootViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}

- (void)viewDidLoad{

[super viewDidLoad];

self.imageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 64, 320, 300)];
[self.view addSubview:_imageView];

self.progressIndicator = [[UIProgressView alloc] initWithProgressViewStyle:UIProgressViewStyleDefault];
_progressIndicator.frame = CGRectMake(50, 500, 220, 50);
[self.view addSubview:_progressIndicator];

UIButton *cancleButton = [UIButton buttonWithType:UIButtonTypeSystem];
cancleButton.frame = CGRectMake(120, 400, 40, 40);
[cancleButton setTitle:@"取消" forState:UIControlStateNormal];
[cancleButton addTarget:self action:@selector(didClickCancleButtonAction:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:cancleButton];

UIButton *downloadButton = [UIButton buttonWithType:UIButtonTypeSystem];
downloadButton.frame = CGRectMake(20, 400, 40, 40);
[downloadButton setTitle:@"下载" forState:UIControlStateNormal];
[downloadButton addTarget:self action:@selector(didClickDownloadButtonAction:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:downloadButton];

UIButton *uploadButton = [UIButton buttonWithType:UIButtonTypeSystem];
uploadButton.frame = CGRectMake(70, 400, 40, 40);
[uploadButton setTitle:@"上传" forState:UIControlStateNormal];
[uploadButton addTarget:self action:@selector(didClickUploadButtonAction:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:uploadButton];

UIButton *resumableButton = [UIButton buttonWithType:UIButtonTypeSystem];
resumableButton.frame = CGRectMake(180, 400, 40, 40);
[resumableButton setTitle:@"恢复" forState:UIControlStateNormal];
[resumableButton addTarget:self action:@selector(didClickResuableButtonAction:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:resumableButton];

UIButton *backgroundLoadButton = [UIButton buttonWithType:UIButtonTypeSystem];
backgroundLoadButton.frame = CGRectMake(220, 400, 80, 40);
[backgroundLoadButton setTitle:@"后台下载" forState:UIControlStateNormal];
[backgroundLoadButton addTarget:self action:@selector(didClickBackgroundButtonAction:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:backgroundLoadButton];

#pragma mark - 如果我们需要利用NSURLSession进行数据传输我们需要：
/**
*  创建一个NSURLSessionConfiguration，用于创建NSSession时设置工作模式(3种)
*  (1)一般模式（default）：工作模式类似于原来的NSURLConnection，可以使用缓存的Cache，Cookie，鉴权。
*  (2)及时模式（ephemeral）：不使用缓存的Cache，Cookie，鉴权。
*  (3)后台模式（background）：在后台完成上传下载，创建Configuration对象的时候需要给一个NSString的ID用于追踪完成工作的Session是哪一个
*/
NSURLSessionConfiguration *sessionConfig = [NSURLSessionConfiguration defaultSessionConfiguration];

/**
*  @网络设置：参考NSURLConnection中的设置项
*  两种创建方法(目前不太懂什么区别)
*  (1)就是根据刚才创建的Configuration创建一个Session，系统默认创建一个新的OperationQueue处理Session的消息
*  (2)可以设定回调的delegate（注意这个回调delegate会被强引用），并且可以设定delegate在哪个OperationQueue回调，如果我们将其
*     设置为[NSOperationQueue mainQueue]就能在主线程进行回调非常的方便
*/
//NSURLSession *session = [NSURLSession sessionWithConfiguration:sessionConfig];
self.urlSession = [NSURLSession sessionWithConfiguration:sessionConfig delegate:self delegateQueue:[NSOperationQueue mainQueue]];
NSURL *url = [NSURL URLWithString:@"http://www.bizhiwa.com/uploads/allimg/2012-01/22021207-1-311536.jpg"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];

/**
*  NSURLSessionUploadTask：上传用的Task，传完以后不会再下载返回结果；
*  NSURLSessionDownloadTask：下载用的Task；
*  NSURLSessionDataTask：可以上传内容，上传完成后再进行下载。
*/
self.sessionDownloadTask = [self.urlSession downloadTaskWithRequest:request];

//  同NSURLConnection一样,有代理方法也就有block方法
//    [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
//    }];

}

#pragma mark 点击下载
- (void)didClickDownloadButtonAction:(UIButton *)button{

// 因为任务默认是挂起状态，需要恢复任务（执行任务）
[_sessionDownloadTask resume];

}

#pragma mark 点击上传
- (void)didClickUploadButtonAction:(UIButton *)button{

//判断imageView是否有内容
if (_imageView.image == nil) {

NSLog(@"image view is empty");
return;

}

// 0. 上传之前在界面上添加指示符
UIActivityIndicatorView *indicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
// 设置位置???
CGSize size = _imageView.bounds.size;
indicator.center = CGPointMake(size.width / 2.0, size.height / 2.0);
[self.imageView addSubview:indicator];
[indicator startAnimating];

// 1. URL
NSURL *url = [NSURL URLWithString:@"http://www.bizhiwa.com/uploads/allimg/2012-01/22021207-1-311536.jpg"];

// 2. Request -> PUT,request的默认操作是GET
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:5.0f];
request.HTTPMethod = @"PUT";

// *** 设置网络请求的身份验证! ***

// 1> 授权字符串

NSString *authStr = @"admin:123456";

// 2> BASE64的编码,避免数据在网络上以明文传输
// iOS中,仅对NSData类型的数据提供了BASE64的编码支持
NSData *authData = [authStr dataUsingEncoding:NSUTF8StringEncoding];
NSString *encodeStr = [authData base64EncodedStringWithOptions:NSDataBase64EncodingEndLineWithCarriageReturn];
NSString *authValue = [NSString stringWithFormat:@"Basic %@", encodeStr];
[request setValue:authValue forHTTPHeaderField:@"Authorization"];

// 3. Session
NSURLSessionConfiguration *sessionConfig = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession *session = [NSURLSession sessionWithConfiguration:sessionConfig delegate:self delegateQueue:[NSOperationQueue mainQueue]];

// 4. UploadTask
NSData *imageData = UIImageJPEGRepresentation(_imageView.image, 0.75);
//  应用block的请求方式
NSURLSessionUploadTask *uploadTask = [session uploadTaskWithRequest:request fromData:imageData completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

// 上传完成后,data参数转换成string就是服务器返回的内容

NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@"OK -> %@", str);

[NSThread sleepForTimeInterval:5.0f];

dispatch_async(dispatch_get_main_queue(), ^{

[indicator stopAnimating];
[indicator removeFromSuperview];

});

}];

// 因为任务默认是挂起状态，需要恢复任务（执行任务）
[uploadTask resume];
}

#pragma mark 点击取消
//  NSURLConnection一旦发送是没法取消的。但是，我们可以很容易的取消掉一个NSURLSessionTask任务
- (void)didClickCancleButtonAction:(UIButton *)button{

/**
*  当取消后，会回调这个URLSession:task:didCompleteWithError:代理方法，通知你去及时更新UI。当取消一个任务后，也
*  十分可能会再一次回调这个代理方法URLSession:downloadTask:didWriteData:BytesWritten:totalBytesExpectedToWrite:
*  当然，didComplete 方法肯定是最后一个回调的。
*/
//    if (_sessionDownloadTask) {
//
//        //  取消下载请求
//        [_sessionDownloadTask cancel];
//        _sessionDownloadTask = nil;
//    }

if (!self.sessionDownloadTask) {

//  停止下载任务,把待恢复的数据保存到一个变量中，方便后面恢复下载使用
[self.sessionDownloadTask cancelByProducingResumeData:^(NSData *resumeData) {

self.partialData = resumeData;
self.sessionDownloadTask = nil;

}];
}
}

#pragma mark  恢复下载(断点续传)
- (void)didClickResuableButtonAction:(UIButton *)button{

if (self.partialData) {

self.sessionDownloadTask = [self.urlSession downloadTaskWithResumeData:self.partialData];
self.partialData = nil;

}else{

NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://pic4.duowan.com/wow/1002/130782267821/130782458426.jpg"]];
self.resumableTask = [self.urlSession downloadTaskWithRequest:request];

}

[self.sessionDownloadTask resume];

}

#pragma mark 后台下载模式
- (void)didClickBackgroundButtonAction:(UIButton *)button{

NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://dldir1.qq.com/qqfile/QQforMac/QQ_V3.1.2.dmg"]];
self.backgroundTask = [[self backgroundSession] downloadTaskWithRequest:request];

[self.backgroundTask resume];
}

#pragma mark - NSURLSessionDownloadTaskDelegate
//  下载完成
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(NSURL *)location{

/**
*******->appDelegete里面的方法
typedef void(^MyBlock)();
@property (copy, nonatomic) MyBlock backgroundURLSessionCompletionHandler;
//  后台请求结束时调用的方法
- (void)application:(UIApplication *)application handleEventsForBackgroundURLSession:(NSString *)identifier completionHandler:(void (^)())completionHandler{

self.backgroundURLSessionCompletionHandler = completionHandler;
}

*/
//  如果是后台NSURLSession,后台请求结束后会调用这个方法,通知你应该更新UI了
if (session == [self backgroundSession]) {

self.backgroundTask = nil;
HMTAppDelegate *appDelegate = (HMTAppDelegate *)[UIApplication sharedApplication].delegate;
if (appDelegate.backgroundURLSessionCompletionHandler) {

void(^handler)() = appDelegate.backgroundURLSessionCompletionHandler;
appDelegate.backgroundURLSessionCompletionHandler = nil;
handler();
}

}

//  这里的缓存处理做的不好,大家按自己的方法处理就行,还有图片的存储以它本身的URL路径为准,这样是不会有重复的
NSFileManager *fileManager = [NSFileManager defaultManager];
NSURL *cachesURLPath = [[fileManager URLsForDirectory:NSCachesDirectory inDomains:NSUserDomainMask] lastObject];
//  根据URL获取到下载的文件名,拼接成沙盒的存储路径(location是下载的临时文件目录,在tmp文件夹里面)
NSURL *destinationPath = [cachesURLPath URLByAppendingPathComponent:[location lastPathComponent]];

NSError *error = nil;
BOOL success = [fileManager moveItemAtURL:location toURL:destinationPath error:&error];
[fileManager removeItemAtURL:location error:NULL];

//  location是下载的临时文件目录,将文件从临时文件夹复制到沙盒
//    BOOL success = [fileManager copyItemAtURL:location toURL:destinationPath error:&error];
if (success) {

dispatch_async(dispatch_get_main_queue(), ^{

UIImage *image = [UIImage imageWithContentsOfFile:[destinationPath path]];
self.imageView.image = image;
//  UIImageView会自动裁剪图片适应它的frame,下面这个属性就是展示原图
self.imageView.contentMode = UIViewContentModeScaleAspectFill;

});
}

}

//  不管任务是否成功，在完成后都会回调这个代理方法
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error{

//  如果error是nil，则证明下载是成功的，否则就要通过它来查询失败的原因。如果下载了一部分，这个error会包含一个NSData对象，如果后面要恢复任务可以用到
if (error == nil) {

dispatch_async(dispatch_get_main_queue(), ^{

self.progressIndicator.hidden = YES;
});
}

}

//  传输进度
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite{

double currentValue = totalBytesWritten / (double)totalBytesExpectedToWrite;
dispatch_async(dispatch_get_main_queue(), ^{
NSLog(@"%f",currentValue);
self.progressIndicator.hidden = NO;
self.progressIndicator.progress = currentValue;
});
}

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

}

#pragma mark - NSURLSession另一个重要的特性：即使当应用不在前台时，你也可以继续传输任务。当然，我们的会话模式也要为后台模式
- (NSURLSession *)backgroundSession{

//  通过给的后台token，我们只能创建一个后台会话，所以这里使用dispatch once block
static NSURLSession *backgroundSession = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{

NSURLSessionConfiguration *config = [NSURLSessionConfiguration backgroundSessionConfiguration:@"com.shinobicontrols.BackgroundDownload.BackgroundSession"];
backgroundSession = [NSURLSession sessionWithConfiguration:config delegate:self delegateQueue:nil];

});

return backgroundSession;
}

- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
// Get the new view controller using [segue destinationViewController].
// Pass the selected object to the new view controller.
}
*/

@end

@不错的NSURLSession文章
iOS 7系列译文：忘记NSURLConnection，拥抱NSURLSession吧！