iOS开发基础44-网络编程之NSURLSession&AFN

在iOS开发中，网络请求是一个非常常见的需求。本文将详细介绍三种网络请求的方式：NSURLConnection、NSURLSession、以及第三方库AFNetworking，并对相关知识点进行补充和分析。

一、NSURLConnection（补充）

NSURLConnection是一种较早期的iOS网络请求工具，但它仍然有很大一部分应用在使用。它可以通过同步和异步方式来进行网络请求。

NSURLConnection的使用

1. 初始化NSURLConnection请求

使用NSURLConnection进行异步请求需要实现相关的Delegate方法：

@interface MyViewController () <NSURLConnectionDataDelegate>
@property (nonatomic, strong) NSMutableData *receivedData;
@end

@implementation MyViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    NSURL *url = [NSURL URLWithString:@"http://example.com"];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
    [connection start];
}

2. NSURLConnectionDataDelegate方法

在实现NSURLConnectionDataDelegate协议时，需要确保各种状态处理的细节。

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    self.receivedData = [[NSMutableData alloc] init];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    [self.receivedData appendData:data];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
    // Handle received data
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    NSLog(@"Connection failed: %@", error.localizedDescription);
}

3. 线程处理

默认情况下，NSURLConnection的回调方法是在主线程中执行的。如果在子线程中发送请求，需要手动将NSURLConnection加入到RunLoop：

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://example.com"]];
    NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:NO];
    [connection scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [connection start];
    [[NSRunLoop currentRunLoop] run];
});

二、NSURLSession

NSURLSession是NSURLConnection的升级版，提供了更加现代、灵活的API，支持后台下载、任务恢复、数据保护等功能。

NSURLSession的使用

1. 创建NSURLSession

有多种方式创建NSURLSession，可以通过共享session、默认session或自定义session：

NSURLSession *session = [NSURLSession sharedSession];

或者创建带有配置的自定义session：

NSURLSessionConfiguration *config = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession *session = [NSURLSession sessionWithConfiguration:config delegate:self delegateQueue:nil];

2. 创建任务并执行

可以创建数据任务、下载任务或上传任务：

NSURL *url = [NSURL URLWithString:@"http://example.com"];
NSURLSessionDataTask *dataTask = [session dataTaskWithURL:url completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
    if (error) {
        NSLog(@"Error: %@", error);
    } else {
        // Handle data
    }
}];
[dataTask resume];

NSURLSessionTask常用方法

[task suspend]; // 暂停任务
[task resume];  // 继续任务
[task cancel];  // 取消任务

取消任务时可以保存进度：

[task cancelByProducingResumeData:^(NSData *resumeData) {
    // Save resumeData
}];

代理方法

NSURLSessionDataDelegate

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition))completionHandler {
    completionHandler(NSURLSessionResponseAllow); // 允许接收数据
}

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data {
    // Handle received data
}

- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error {
    if (error) {
        NSLog(@"Error: %@", error);
    } else {
        // Task completed successfully
    }
}

NSURLSessionDownloadDelegate

- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite {
    // Handle download progress
}

- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(NSURL *)location {
    // Handle file download completion
}

NSURLSessionTaskDelegate

- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didSendBodyData:(int64_t)bytesSent totalBytesSent:(int64_t)totalBytesSent totalBytesExpectedToSend:(int64_t)totalBytesExpectedToSend {
    // Handle upload progress
}

断点下载

断点下载在需要暂停和恢复任务时非常有用。以下是一个简单的断点下载实现：

#import "ViewController.h"

@interface ViewController () <NSURLSessionDataDelegate>

@property (nonatomic, strong) NSURLSession *session;
@property (nonatomic, strong) NSURLSessionDataTask *dataTask;
@property (nonatomic, strong) NSOutputStream *outputStream;
@property (nonatomic, assign) NSUInteger totalLength;
@property (nonatomic, assign) NSUInteger currentLength;
@property (nonatomic, strong) NSData *resumeData;
@property (weak, nonatomic) IBOutlet UIProgressView *progressView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.currentLength = [self getFileSizeAtPath:[self filePath]];
}

- (IBAction)startDownload:(id)sender {
    [self.dataTask resume];
}

- (IBAction)pauseDownload:(id)sender {
    [self.dataTask suspend];
}

- (IBAction)resumeDownload:(id)sender {
    if (self.resumeData) {
        self.dataTask = [self.session downloadTaskWithResumeData:self.resumeData];
    }
    [self.dataTask resume];
}

- (NSUInteger)getFileSizeAtPath:(NSString *)path {
    if ([[NSFileManager defaultManager] fileExistsAtPath:path]) {
        NSDictionary *attributes = [[NSFileManager defaultManager] attributesOfItemAtPath:path error:nil];
        return [attributes[NSFileSize] unsignedIntegerValue];
    }
    return 0;
}

- (NSString *)filePath {
    return [NSTemporaryDirectory() stringByAppendingPathComponent:@"downloadedFile"];
}

#pragma mark - NSURLSessionDataDelegate

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition))completionHandler {
    self.totalLength = response.expectedContentLength + self.currentLength;
    self.outputStream = [NSOutputStream outputStreamToFileAtPath:[self filePath] append:YES];
    [self.outputStream open];
    completionHandler(NSURLSessionResponseAllow);
}

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data {
    [self.outputStream write:data.bytes maxLength:data.length];
    self.currentLength += data.length;
    self.progressView.progress = 1.0 * self.currentLength / self.totalLength;
}

- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error {
    if (!error) {
        NSLog(@"Download completed.");
    } else {
        NSLog(@"Download failed: %@", error.localizedDescription);
    }
    [self.outputStream close];
}

#pragma mark - Lazy Loading

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

- (NSURLSessionDataTask *)dataTask {
    if (!_dataTask) {
        NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://example.com/path/to/file"]];
        NSString *range = [NSString stringWithFormat:@"bytes=%zd-", self.currentLength];
        [request setValue:range forHTTPHeaderField:@"Range"];
        _dataTask = [self.session dataTaskWithRequest:request];
    }
    return _dataTask;
}

@end

三、AFNetworking

AFNetworking是一个基于NSURLSession的流行iOS网络请求库，提供了更简洁高效的API，用于处理网络请求、文件下载、上传和序列化等操作。

AFNetworking的使用

1. 安装AFNetworking

推荐使用CocoaPods来安装AFNetworking：

pod 'AFNetworking', '~> 4.0'

然后运行pod install。

2. 使用AFHTTPRequestOperationManager进行请求

GET请求

AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
[manager GET:@"http://example.com/api" parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
    NSLog(@"JSON: %@", responseObject);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    NSLog(@"Error: %@", error);
}];

POST请求

AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
NSDictionary *parameters = @{@"foo": @"bar"};
[manager POST:@"http://example.com/api" parameters:parameters success:^(AFHTTPRequestOperation *operation, id responseObject) {
    NSLog(@"JSON: %@", responseObject);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    NSLog(@"Error: %@", error);
}];

3. 使用AFHTTPSessionManager进行请求

GET请求

AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
[manager GET:@"http://example.com/api" parameters:nil headers:nil progress:nil success:^(NSURLSessionDataTask *task, id responseObject) {
    NSLog(@"JSON: %@", responseObject);
} failure:^(NSURLSessionDataTask *task, NSError *error) {
    NSLog(@"Error: %@", error);
}];

POST请求

AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
NSDictionary *parameters = @{@"foo": @"bar"};
[manager POST:@"http://example.com/api" parameters:parameters headers:nil progress:nil success:^(NSURLSessionDataTask *task, id responseObject) {
    NSLog(@"JSON: %@", responseObject);
} failure:^(NSURLSessionDataTask *task, NSError *error) {
    NSLog(@"Error: %@", error);
}];

4. 文件下载

AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://example.com/file.zip"]];
NSURLSessionDownloadTask *downloadTask = [manager downloadTaskWithRequest:request progress:nil destination:^NSURL *(NSURL *targetPath, NSURLResponse *response) {
    NSURL *documentsDirectoryURL = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:NO error:nil];
    return [documentsDirectoryURL URLByAppendingPathComponent:[response suggestedFilename]];
} completionHandler:^(NSURLResponse *response, NSURL *filePath, NSError *error) {
    if (!error) {
        NSLog(@"File downloaded to: %@", filePath);
    } else {
        NSLog(@"Error: %@", error);
    }
}];
[downloadTask resume];

5. 文件上传

AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
NSDictionary *parameters = @{@"foo": @"bar"};
[manager POST:@"http://example.com/upload" parameters:parameters headers:nil constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
    NSURL *fileURL = [NSURL fileURLWithPath:@"filePath"];
    [formData appendPartWithFileURL:fileURL name:@"file" error:nil];
} progress:nil success:^(NSURLSessionDataTask *task, id responseObject) {
    NSLog(@"Success: %@", responseObject);
} failure:^(NSURLSessionDataTask *task, NSError *error) {
    NSLog(@"Error: %@", error);
}];

6. 序列化

AFNetworking默认支持JSON数据的自动序列化和反序列化，但也提供了灵活的自定义方法：

AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
manager.responseSerializer = [AFXMLParserResponseSerializer serializer];
// or
manager.responseSerializer = [AFHTTPResponseSerializer serializer];

7. 网络状态检测

AFNetworkReachabilityManager *manager = [AFNetworkReachabilityManager sharedManager];
[manager setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {
    switch (status) {
        case AFNetworkReachabilityStatusReachableViaWWAN:
            NSLog(@"Cellular");
            break;
        case AFNetworkReachabilityStatusReachableViaWiFi:
            NSLog(@"WiFi");
            break;
        case AFNetworkReachabilityStatusNotReachable:
            NSLog(@"No Connection");
            break;
        default:
            break;
    }
}];
[manager startMonitoring];

六、总结

在iOS网络请求中，NSURLConnection、NSURLSession和AFNetworking各有特点：

NSURLConnection是最基础的方式，但需要手动管理较多的细节。
NSURLSession提供了更多现代化特性和更好的性能。
AFNetworking基于NSURLSession，提供了更简洁的API，简化了常见操作。

选择哪种方式取决于具体的项目需求和开发者的习惯。

posted @ 2015-08-24 19:18 Mr.陳阅读(1255) 评论(0) 收藏举报

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iOS开发基础44-网络编程之NSURLSession&AFN

一、NSURLConnection（补充）

NSURLConnection的使用

1. 初始化NSURLConnection请求

2. NSURLConnectionDataDelegate方法

3. 线程处理

二、NSURLSession

NSURLSession的使用

1. 创建NSURLSession

2. 创建任务并执行

NSURLSessionTask常用方法

代理方法

NSURLSessionDataDelegate

NSURLSessionDownloadDelegate

NSURLSessionTaskDelegate

断点下载

三、AFNetworking

AFNetworking的使用

1. 安装AFNetworking

2. 使用AFHTTPRequestOperationManager进行请求

GET请求

POST请求

3. 使用AFHTTPSessionManager进行请求

GET请求

POST请求

4. 文件下载

5. 文件上传

6. 序列化

7. 网络状态检测

六、总结

公告