A collection of classes useful for fetching and persisting file data. Built on top of NSURLSession.

Features

• Download data directly to disk from an NSURL or NSURLRequest.
• Files continue to download when the app is suspended.
• Data is automatically moved to persistent storage on disk.
• Data can be encrypted using standard iOS disk encryption.
• If protected file access is unavailable, data is queued for encryption at a later date.
• Specify a disk size limit in bytes. If data on disk exceeds this limit, specific files are chosen and evicted using a combination of the file's last access date and file size.
• Specify an identifier when fetching a file. This identifier can be used to check for the existence of a file on disk, or to evict a file.
• Specify an optional file group for each file to associate it with other files.
• Specify a task priority for a fetch.
• Initiate a manual eviction of a file with an identifier and file group, evict all files in a file group, or evict the entire disk cache.
• Ignore the results of a currently running fetch operation. This uninstalls the completion handler, but continues downloading the file.
• If a fetch is in progress, and another fetch is initiated for the same resource, the second completion handler is installed on the currently running fetch, preventing duplicate data.
• Inject existing data to be persisted by the file manager.
• Image manager uses a file manager to fetch / persist image data specifically.

Usage

Initialization & Configuration:

self.fileManager = [[SFSFileManager alloc] init];
self.fileManager.usesEncryptionByDefault = YES;
self.fileManager.diskSizeLimit = 512 * 1024 * 1024; // 512 MB

Simplest Fetch:

NSURL *url = [NSURL URLWithString:@"http://placekitten/600/500"];
[self.fileManager fetchFileDataAtURL:url withCompletion:^(NSURL *fileURL, NSError *error) {

    // data fetched using '[url absoluteString]' as the identifier 
    // and 'SFSFileManagerDefaultFileGroup' as the file group
}];

Complex Fetch:

NSURL *url = [NSURL URLWithString:@"http://myapi.com/users"];
NSMutableURLRequest *urlRequest = [NSMutableURLRequest requestWithURL:url];
[request setValue:<#auth string#> forHTTPHeaderField:@"Authorization"];

SFSFileFetchRequest *request = [SFSFileFetchRequest request];
request.urlRequest = urlRequest;
request.identifier = @"12345";
request.fileGroup = @"userDataGroup";
request.encryptionPolicy = SFSFileFetchRequestEncryptionPolicyUseEncryption;
request.taskPriority = SFSFileFetchRequestTaskPriorityHigh;

__typeof__(self) __weak weakSelf = self;
id<SFSTask> task = [self.fileManager fetchFileDataUsingFetchRequest:request withCompletion:^(NSURL *fileURL, NSError *error) {

    [weakSelf useFileAtURL:fileURL error:error];
}];

// Some time later...

if ([task isRunning])
{
    [task ignoreResults]; //will cause the above completion block to not be called, but will not cancel the request.
    // or
    [task cancelRequest];
}

Image Manager:

// using 'nil' causes a file manager to be created for you.
self.imageManager = [[SFSImageManager alloc] initWithFileManager:nil]; 

NSURL *url = [NSURL URLWithString:@"http://placekitten/600/500"];

__typeof__(self) __weak weakSelf = self;
[self.imageManager fetchImageAtURL:url withCompletion:^(UIImage *image, NSError *error) {

    // completion is executed on the main thread.
    weakSelf.imageView.image = image;
}];

Integration

By far, the easiest way to integrate SpaceFactoryNetworking is using CocoaPods:

# Example Podfile
pod 'SpaceFactoryNetworking'

Otherwise, you can clone this repo, and import files from the 'SpaceFactoryNetworking/Core' folder.

Collaborate

You are welcome to submit pull requests to this project. If you are considering doing so, please reach out to me at [email protected]. I'd like to touch base.

Potential additions:

• Unit Tests (much needed)
• More screens in the Example app to demonstrate functionality
• Callbacks to report progress on a download

Known Issues:

• File access may not fail gracefully if the protected file is accessed while the app is in the background and the device is locked.