iOS网络编程(六) NSURLSession详解 · iOS 高级

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！](http://jishu.zol.com.cn/201091.html)