AFNetworking 3.0 AFHTTPSessionManager 使用 NSOperation

Question

我现在被困了一段时间，我需要帮助。所以在 AFNetworking 2.0 我们有AFHTTPRequestOperation 所以我可以很容易地使用NSOperationQueue 并且有一些依赖。所以我们现在只有AFHTTPSessionManager和NSURLSession，它们不是NSOperation的子类。我有类APIClient 是AFHTTPSessionManager 的子类。我将该类用作sharedClient 的单例。我已经覆盖了 GET 和 POST，例如 GET 看起来是这样的：

- (NSURLSessionDataTask *)GET:(NSString *)URLString
               parameters:(NSDictionary *)parameters
                  success:(void (^)(NSURLSessionDataTask *task, id responseObject))success
                  failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure {
NSURLSessionDataTask *task = [super GET:URLString parameters:parameters success:^(NSURLSessionDataTask *task, id responseObject) {
    success(task, responseObject);
} failure:^(NSURLSessionDataTask *task, NSError *error) {
    failure(task, [Response createErrorWithAFNetworkingError:error]);
}];

return task;
}

您知道如何以这种方式（如果可能的话）将其包装为NSOperation 吗？所以我想做的是-我希望能够并行运行两个网络调用，然后再进行另一个方法调用，该方法调用取决于前两个调用的第二个网络调用。你知道什么是最好的方法吗？

Answer 1

我已经编写了一组快速的类 (https://github.com/robertmryan/AFHTTPSessionOperation/)，它们将 AFHTTPSessionManager 请求包装在异步 NSOperation 子类中。然后，您可以使用它来享受maxConcurrentOperation 约束或操作依赖关系。

例如，下面是一个示例，我们发出两个并发请求，并根据这两个请求的完成进行完成操作：

//  ViewController.m

#import "ViewController.h"
#import "AFNetworking.h"
#import "AFHTTPSessionOperation.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    NSString *urlString1 = @"...";
    NSString *urlString2 = @"...";

    AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];

    NSOperationQueue *queue = [[NSOperationQueue alloc] init];
    queue.name = @"AFHTTPSessionManager queue";

    NSOperation *completionOperation = [NSBlockOperation blockOperationWithBlock:^{
        NSLog(@"All done");
    }];

    NSOperation *op1 = [AFHTTPSessionOperation operationWithManager:manager HTTPMethod:@"GET" URLString:urlString1 parameters:nil uploadProgress:nil downloadProgress:nil success:^(NSURLSessionDataTask *task, id responseObject) {
        NSLog(@"finished 1");
    } failure:^(NSURLSessionDataTask *task, NSError *error) {
        NSLog(@"failed 1 - error = %@", error.localizedDescription);
    }];
    [completionOperation addDependency:op1];

    NSOperation *op2 = [AFHTTPSessionOperation operationWithManager:manager HTTPMethod:@"GET" URLString:urlString2 parameters:nil uploadProgress:nil downloadProgress:nil success:^(NSURLSessionDataTask *task, id responseObject) {
        NSLog(@"finished 2");
    } failure:^(NSURLSessionDataTask *task, NSError *error) {
        NSLog(@"failed 2 - error = %@", error.localizedDescription);
    }];
    [completionOperation addDependency:op2];

    [queue addOperations:@[op1, op2] waitUntilFinished:false];
    [[NSOperationQueue mainQueue] addOperation:completionOperation];  // do this on whatever queue you want, but often you're updating UI or model objects, in which case you'd use the main queue
}

@end

值得注意的是，由于您只处理两个请求，您还可以使用调度组来完成同样的事情：

//  ViewController.m

#import "ViewController.h"
#import "AFNetworking.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    NSString *urlString1 = @"...";
    NSString *urlString2 = @"...";

    AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];

    dispatch_group_t group = dispatch_group_create();

    dispatch_group_enter(group);
    [manager GET:urlString1 parameters:nil progress:nil success:^(NSURLSessionDataTask * _Nonnull task, id  _Nullable responseObject) {
        NSLog(@"finished 1");
        dispatch_group_leave(group);
    } failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
        NSLog(@"failed 1 - error = %@", error.localizedDescription);
        dispatch_group_leave(group);
    }];

    dispatch_group_enter(group);
    [manager GET:urlString2 parameters:nil progress:nil success:^(NSURLSessionDataTask * _Nonnull task, id  _Nullable responseObject) {
        NSLog(@"finished 2");
        dispatch_group_leave(group);
    } failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
        NSLog(@"failed 2 - error = %@", error.localizedDescription);
        dispatch_group_leave(group);
    }];

    dispatch_group_notify(group, dispatch_get_main_queue(), ^{
        NSLog(@"All done");
    });
}

@end

使用调度组，您只需要注意success 和failure 块中的每个路径都调用dispatch_group_leave。