AFNetwork框架（零）使用NSURLSession进行网络请求

我们首先来看一下一个简单的NSURLSession请求代码&＃xff1a;

NSURLSession *session &＃61; [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[[NSOperationQueue alloc] init]];NSURLRequest *request &＃61; [[NSURLRequest alloc]initWithURL:[NSURL URLWithString:bigPic]];NSURLSessionDataTask *dataTask &＃61; [session dataTaskWithRequest:request];[dataTask resume];

我们的NSRULSession 网络请求系统包括一个session、一个configuration、一个Task已经Task附带的delegate。

• 一个NSURLSession,总共只有一个类&＃xff0c;也是最核心的类&＃xff0c;他有一个对应的代理NSURLSessionDelegate。
• 一个NSURLSessionConfiguration,总共有三种模式。
• 一个NSURLSessionTask。NSURLSessionTask是抽闲类,对应的代理NSURLSessionTaskDelegate。我们具体使用的时候&＃xff0c;会使用他的三种子类&＃xff0c;而且每个子类都有对应的delegate。

NSURLSession

//初始化部分
&＃64;property (class, readonly, strong) NSURLSession *sharedSession;
&＃43; (NSURLSession *)sessionWithConfiguration:(NSURLSessionConfiguration *)configuration;
&＃43; (NSURLSession *)sessionWithConfiguration:(NSURLSessionConfiguration *)configuration delegate:(nullable id )delegate delegateQueue:(nullable NSOperationQueue *)queue;//属性部分
&＃64;property (readonly, retain) NSOperationQueue *delegateQueue;
&＃64;property (nullable, readonly, retain) id delegate;
&＃64;property (readonly, copy) NSURLSessionConfiguration *configuration;//dataTask部分
- (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request;
- (NSURLSessionDataTask *)dataTaskWithURL:(NSURL *)url;//uploadTask部分
- (NSURLSessionUploadTask *)uploadTaskWithRequest:(NSURLRequest *)request fromFile:(NSURL *)fileURL;
- (NSURLSessionUploadTask *)uploadTaskWithRequest:(NSURLRequest *)request fromData:(NSData *)bodyData;
- (NSURLSessionUploadTask *)uploadTaskWithStreamedRequest:(NSURLRequest *)request;//downloadTask部分
- (NSURLSessionDownloadTask *)downloadTaskWithRequest:(NSURLRequest *)request;
- (NSURLSessionDownloadTask *)downloadTaskWithURL:(NSURL *)url;
- (NSURLSessionDownloadTask *)downloadTaskWithResumeData:(NSData *)resumeData;

从上面NSURLSession初始化一个请求的时候&＃xff0c;我们发现NSURLSessionTask并不能直接使用&＃xff0c;只能使用他的子类。具体如下&＃xff1a;

• NSURLSessionTask抽象类。有对应的代理NSURLSessionTaskDelegate,而且这个代理继承了NSURLSessionDelegate代理。
• NSURLSessionDataTask是NSURLSessionTask的子类。有对应的代理NSURLSessionTaskDelegate,而且这个代理继承了NSURLSessionTaskDelegate代理。我们一般网络请求&＃xff0c;就用这个类。
• NSURLSessionDownloadTask是NSURLSessionTask的子类。有对应的代理NSURLSessionDownloadDelegate,而且这个代理继承了NSURLSessionTaskDelegate代理。这个主要用于下载大文件等。
• NSURLSessionUploadTask是NSURLSessionDataTask的子类。有对应的代理及时父类代理NSURLSessionDownloadDelegate。这个主要用于处理上传请求如上传图片。

static NSString *const smallPic &＃61; &＃64;"http://i1.piimg.com/4851/97aef4680d359905.png";&＃64;interface ViewController ()
&＃64;property (weak, nonatomic) IBOutlet UIImageView *imageView;
&＃64;property(nonatomic,strong)NSMutableData *data;
&＃64;end&＃64;implementation ViewController- (void)viewDidLoad {[super viewDidLoad];// Do any additional setup after loading the view, typically from a nib.
}- (IBAction)requestDataTest:(id)sender {[self clear];NSURLSession *session &＃61; [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[[NSOperationQueue alloc] init]];NSURLRequest *request &＃61; [[NSURLRequest alloc]initWithURL:[NSURL URLWithString:bigPic]];NSURLSessionDataTask *dataTask &＃61; [session dataTaskWithRequest:request];[dataTask resume];
}- (IBAction)requestDownloadTest:(id)sender {[self clear];NSURLSession *session &＃61; [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[[NSOperationQueue alloc] init]];NSURLRequest *request &＃61; [[NSURLRequest alloc]initWithURL:[NSURL URLWithString:bigPic]];NSURLSessionDownloadTask *dataTask &＃61; [session downloadTaskWithRequest:request];[dataTask resume];
}-(IBAction)requestBlockTaskTest:(id)sender{[self clear];NSURLSession *session &＃61; [NSURLSession sharedSession];NSURLRequest *request &＃61; [[NSURLRequest alloc]initWithURL:[NSURL URLWithString:bigPic]];NSURLSessionDataTask *dataTask &＃61; [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {UIImage *image &＃61; [[UIImage alloc]initWithData:data];self.imageView.image &＃61; image;}];[dataTask resume];
}-(void)clear{self.imageView.image &＃61; nil;
}//&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;NSURLSessionDelegate&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;
#pragma NSURLSessionDelegate
//当一个session遇到系统错误或者未检测到的错误的时候&＃xff0c;就会调用这个方法。
- (void)URLSession:(NSURLSession *)session didBecomeInvalidWithError:(nullable NSError *)error{}
//当请求需要认证、或者https证书认证的时候&＃xff0c;我们就需要在这个方法里面处理。
- (void)URLSession:(NSURLSession *)session didReceiveChallenge:(NSURLAuthenticationChallenge *)challengecompletionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition, NSURLCredential * _Nullable credential))completionHandler{}
//如果应用进入后台、这个方法会被调用。我们在这里可以对session发起的请求做各种操作比如请求完成的回调等。
- (void)URLSessionDidFinishEventsForBackgroundURLSession:(NSURLSession *)session {}//&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;NSURLSessionTaskDelegate&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;
#pragma NSURLSessionTaskDelegate
/*当请求重定向的时候调用这个方法。我们必须设置一个新的&＃96;NSURLRequest&＃96;对象传入completionHandler来重定向新的请求&＃xff0c;但是当&＃96;session&＃96;是background模式的时候&＃xff0c;这个方法不会被调用。*/
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task
willPerformHTTPRedirection:(NSHTTPURLResponse *)responsenewRequest:(NSURLRequest *)requestcompletionHandler:(void (^)(NSURLRequest * _Nullable))completionHandler{}
/*当请求需要认证的时候调用这个方法。如果没有实现这个代理&＃xff0c;那么请求认证这个过程不会被调用。*/
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task
didReceiveChallenge:(NSURLAuthenticationChallenge *)challengecompletionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition, NSURLCredential * _Nullable credential))completionHandler{}
/*如果请求需要一个新的请求体时&＃xff0c;这个方法就会被调用。比如认证失败的时候&＃xff0c;我们可以通过这个机会从新认证。*/
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)taskneedNewBodyStream:(void (^)(NSInputStream * _Nullable bodyStream))completionHandler{}
/*当我们上传数据的时候&＃xff0c;我们可以通过这个代理方法获取上传进度。*/
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)taskdidSendBodyData:(int64_t)bytesSenttotalBytesSent:(int64_t)totalBytesSent
totalBytesExpectedToSend:(int64_t)totalBytesExpectedToSend{NSLog(&＃64;"");
}
/*当task的统计信息收集好了以后&＃xff0c;调用这个方法。*/
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didFinishCollectingMetrics:(NSURLSessionTaskMetrics *)metrics {}
/*当一个task出错的时候&＃xff0c;会调用这个方法。如果error是nil&＃xff0c;也会调用这个方法&＃xff0c;表示task完成。*/
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task
didCompleteWithError:(nullable NSError *)error{NSLog(&＃64;"数据返回以后&＃xff0c;不管有错没错都回调用&＃xff0c;如果没错&＃xff0c;error及时nil");if (self.data) {self.imageView.image &＃61; [UIImage imageWithData:self.data];self.data &＃61; nil;}
}//&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;NSURLSessionDataDelegate&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;
#pragma NSURLSessionDataDelegate
/*当一个task接收到返回信息。当所有信息都接收完毕以后&＃xff0c;completionHandler会被调用。我们可以在这里取消一个网络请求或者把一个datatask转换为downloadtask。如果没有实现这个代理方法&＃xff0c;我们也可以通过task的response属性获取到对应的数据。background模式的uploadtask不会调用这个方法。*/
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask
didReceiveResponse:(NSURLResponse *)responsecompletionHandler:(void (^)(NSURLSessionResponseDisposition disposition))completionHandler{self.data &＃61; nil;self.data &＃61; [NSMutableData data];// 允许处理服务器的响应&＃xff0c;才会继续接收服务器返回的数据completionHandler(NSURLSessionResponseAllow);
}
/*当一个datatask转换为一个downloadtask以后会调用。*/
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask
didBecomeDownloadTask:(NSURLSessionDownloadTask *)downloadTask{}
/*暂时忽略&＃xff0c;这个是和数据流相关的。不管了*/
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask
didBecomeStreamTask:(NSURLSessionStreamTask *)streamTask{}
/*当data可以使用的时候&＃xff0c;调用这个方法。我们可以在这里获取data。*/
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTaskdidReceiveData:(NSData *)data{[self.data appendData:data];NSLog(&＃64;"具体数据在URLSession:(NSURLSession *)session task:(NSURLSessionTask *)taskdidCompleteWithError:(nullable NSError *)error处理");
}
/*允许我们在这里调用completionHandler缓存data&＃xff0c;或者传入nil来禁止缓存*/
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTaskwillCacheResponse:(NSCachedURLResponse *)proposedResponsecompletionHandler:(void (^)(NSCachedURLResponse * _Nullable cachedResponse))completionHandler{}
//&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;NSURLSessionDownloadTask&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;
#pragma NSURLSessionDownloadTask
/*当一个下载task任务完成以后&＃xff0c;这个方法会被调用。我们可以在这里移动或者复制download的数据*/
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
didFinishDownloadingToURL:(NSURL *)location{NSString *path &＃61; location.absoluteString;UIImage *image &＃61; [[UIImage alloc]initWithData:[NSData dataWithContentsOfURL:location]];self.imageView.image &＃61; image;NSLog(&＃64;"数据下载完成以后&＃xff0c;会保存在一个location的地方。%&＃64;",location);
}
/*获取下载进度*/
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTaskdidWriteData:(int64_t)bytesWrittentotalBytesWritten:(int64_t)totalBytesWritten
totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite{NSLog(&＃64;"总得数据大小%lld----",bytesWritten);
}
/*重启一个下载任务(比如下载一半后停止然后过一点时间继续)。如果下载出错&＃xff0c;&＃96;NSURLSessionDownloadTaskResumeData&＃96;里面包含重新开始下载的数据。*/
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTaskdidResumeAtOffset:(int64_t)fileOffset
expectedTotalBytes:(int64_t)expectedTotalBytes{}
&＃64;end

URLRequest的参数的两种请求方式

JSONEncoding.default&＃xff1a;将参数编码成Data之后放在Request的body里面

URLEncoding.default: 将参数直接放在Request的URL上