AFHTTPSessionOperation

Introduction

AFHTTPSessionOperation is a NSOperation subclass for HTTP requests added to AFNetworking's AFHTTPSessionManager. AFURLSessionOperation is a NSOperation subclass for data, upload, and download requests implemented in AFURLSessionManager.

This has been updated for AFNetworking 3.x. See 2.x branch of this repo if you're using AFNetworking 2.x.

When using AFHTTPRequestOperationManager (now retired), you enjoy NSOperation capabilities, but when using AFHTTPSessionManager, you don't. This is somewhat understandable (as NSURLSession introduces background requests, and that's incompatible with NSOperation-based approaches), but when performing requests in the foreground, it's useful to have NSOperation-style capabilities. This class makes that possible.

Usage

AFHTTPSessionOperation

AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
manager.responseSerializer = [AFImageResponseSerializer serializer];

NSOperationQueue *queue = [[NSOperationQueue alloc] init];
queue.maxConcurrentOperationCount = 3;

NSArray *filenames = @[@"file1.jpg", @"file2.jpg", @"file3.jpg", @"file4.jpg", @"file5.jpg", @"file6.jpg"];

for (NSString *filename in filenames)  {
    NSString *urlString = [@"http://example.com" stringByAppendingPathComponent:filename];
    NSOperation *operation = [AFHTTPSessionOperation operationWithManager:manager HTTPMethod:@"GET" URLString:urlString parameters:nil uploadProgress:nil downloadProgress:^(NSProgress *downloadProgress) {
        NSLog(@"%@: %.1f", filename, downloadProgress.fractionCompleted * 100.0);
    } success:^(NSURLSessionDataTask *task, id responseObject) {
        NSLog(@"%@: %@", filename, NSStringFromCGSize([responseObject size]));
    } failure:^(NSURLSessionDataTask *task, NSError *error) {
        NSLog(@"%@: %@", filename, error.localizedDescription);
    }];
    [queue addOperation:operation];
}

AFURLSessionOperation

AFURLSessionManager *manager = [[AFURLSessionManager alloc] init];

NSOperationQueue *queue = [[NSOperationQueue alloc] init];
queue.maxConcurrentOperationCount = 3;

NSArray *filenames = @[@"file1.jpg", @"file2.jpg", @"file3.jpg", @"file4.jpg", @"file5.jpg", @"file6.jpg"];

for (NSString *filename in filenames)  {
    NSString *urlString = [@"http://example.com" stringByAppendingPathComponent:filename];
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:urlString]];

    NSOperation *operation = [AFURLSessionOperation downloadOperationWithManager:manager request:request progress:^(NSProgress * _Nonnull downloadProgress) {
        NSLog(@"%@: %.1f", filename, downloadProgress.fractionCompleted * 100.0);
    } destination:^NSURL * _Nonnull(NSURL * _Nonnull targetPath, NSURLResponse * _Nonnull response) {
        NSError *error;
        NSURL *documentsURL = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:false error:&error];
        return [documentsURL URLByAppendingPathComponent:filename];
    } completionHandler:^(NSURLResponse * _Nonnull response, NSURL * _Nullable filePath, NSError * _Nullable error) {
        NSLog(@"%@ done %@", filename, (error.localizedDescription ?: @""));
    }];
    [queue addOperation:operation];
}

Progress and completion

The progress of a series of requests can be accomplished by creating your own NSProgress object and then call addChild for the NSProgress objects of all of the tasks that are created. You can then add an observer to the fractionCompleted of your NSProgress.

To determine when the downloads are done, you can add an operation (e.g. a NSBlockOperation) and then make it dependent upon all of the other operations that were added to the queue.

To illustrate this, a Swift 2 implementation might look like so. The Objective-C implementation is equivalent.

import UIKit

private var observerContext = 0

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        progress = NSProgress()
        progress.addObserver(self, forKeyPath: "fractionCompleted", options: .New, context: &observerContext)

        downloadFiles()
    }

    private var progress: NSProgress!

    deinit {
        progress?.removeObserver(self, forKeyPath: "fractionCompleted")
    }

    private func downloadFiles() {
        let filenames = ["as17-134-20380.jpg", "as17-140-21497.jpg", "as17-148-22727.jpg"]

        let baseURL = NSURL(string: "http://example.com/path")!

        let queue = NSOperationQueue()
        queue.maxConcurrentOperationCount = 4

        progress.totalUnitCount = Int64(filenames.count)
        progress.completedUnitCount = 0

        let manager = AFHTTPSessionManager()
        manager.responseSerializer = AFImageResponseSerializer()

        let completionOperation = NSBlockOperation {
            print("done")
        }

        for filename in filenames {
            let url = baseURL.URLByAppendingPathComponent(filename)
            let operation = AFHTTPSessionOperation(manager: manager, HTTPMethod: "GET", URLString: url.absoluteString, parameters: nil, uploadProgress: nil, downloadProgress: nil, success:
                { (task, responseObject) -> Void in
                    print("\(filename): \(NSStringFromCGSize((responseObject as! UIImage).size))")
                }, failure: { task, error in
                    print("\(filename): \(error)")
                })
            queue.addOperation(operation)
            completionOperation.addDependency(operation)
            progress.addChild(manager.downloadProgressForTask(operation.task!)!, withPendingUnitCount: 1)
        }

        queue.addOperation(completionOperation)
    }

    override func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutablePointer<Void>) {
        if context == &observerContext {
            if keyPath == "fractionCompleted" {
                let percent = change![NSKeyValueChangeNewKey] as! Double
                print("\(percent)")
            }
        } else {
            super.observeValueForKeyPath(keyPath, ofObject: object, change: change, context: context)
        }
    }

}

Note, this is a mix and match situation, where you can use either NSProgress or completion handler or both or neither. I just depends upon your needs.

Reference

As contemplated in AFNetworking issue #1504.

License

The MIT License (MIT)

Copyright (c) 2015 Rob Ryan

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.