Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

Awesome Lists | Featured Topics | Projects

https://github.com/hyperoslo/Cache

:package: Nothing but Cache.
https://github.com/hyperoslo/Cache

cache cache-storage disk-cache ios memory-cache swift

Last synced: 3 months ago
JSON representation

:package: Nothing but Cache.

Awesome Lists containing this project

README 

        
![Cache](https://github.com/hyperoslo/Cache/blob/master/Resources/CachePresentation.png)



[![CI Status](https://circleci.com/gh/hyperoslo/Cache.png)](https://circleci.com/gh/hyperoslo/Cache)

[![Version](https://img.shields.io/cocoapods/v/Cache.svg?style=flat)](http://cocoadocs.org/docsets/Cache)

[![Carthage Compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage)

[![License](https://img.shields.io/cocoapods/l/Cache.svg?style=flat)](http://cocoadocs.org/docsets/Cache)

[![Platform](https://img.shields.io/cocoapods/p/Cache.svg?style=flat)](http://cocoadocs.org/docsets/Cache)

[![Documentation](https://img.shields.io/cocoapods/metrics/doc-percent/Cache.svg?style=flat)](http://cocoadocs.org/docsets/Cache)

![Swift](https://img.shields.io/badge/%20in-swift%205-orange.svg)



## Table of Contents



* [Description](#description)

* [Key features](#key-features)

* [Usage](#usage)

  * [Storage](#storage)

  * [Configuration](#configuration)

  * [Sync APIs](#sync-apis)

  * [Async APIs](#async-apis)

  * [Expiry date](#expiry-date)

* [Observations](#observations)

  * [Storage observations](#storage-observations)

  * [Key observations](#key-observations)

* [Handling JSON response](#handling-json-response)

* [What about images?](#what-about-images)

* [Installation](#installation)

* [Author](#author)

* [Contributing](#contributing)

* [License](#license)



## Description



Cache Icon



**Cache** doesn't claim to be unique in this area, but it's not another monster

library that gives you a god's power. It does nothing but caching, but it does it well. It offers a good public API

with out-of-box implementations and great customization possibilities. `Cache` utilizes `Codable` in Swift 4 to perform serialization.



Read the story here [Open Source Stories: From Cachable to Generic Storage in Cache](https://medium.com/hyperoslo/open-source-stories-from-cachable-to-generic-storage-in-cache-418d9a230d51)



## Key features



- [x] Work with Swift 4 `Codable`. Anything conforming to `Codable` will be saved and loaded easily by `Storage`.

- [x] Hybrid with memory and disk storage.

- [X] Many options via `DiskConfig` and `MemoryConfig`.

- [x] Support `expiry` and clean up of expired objects.

- [x] Thread safe. Operations can be accessed from any queue.

- [x] Sync by default. Also support Async APIs.

- [x] Extensive unit test coverage and great documentation.

- [x] iOS, tvOS and macOS support.



## Usage



### Storage



`Cache` is built based on [Chain-of-responsibility pattern](https://en.wikipedia.org/wiki/Chain-of-responsibility_pattern), in which there are many processing objects, each knows how to do 1 task and delegates to the next one, so can you compose Storages the way you like.



For now the following Storage are supported



- `MemoryStorage`: save object to memory.

- `DiskStorage`: save object to disk.

- `HybridStorage`: save object to memory and disk, so you get persistented object on disk, while fast access with in memory objects.

- `SyncStorage`: blocking APIs, all read and write operations are scheduled in a serial queue, all sync manner.

- `AsyncStorage`: non-blocking APIs, operations are scheduled in an internal queue for serial processing. No read and write should happen at the same time.



Although you can use those Storage at your discretion, you don't have to. Because we also provide a convenient `Storage` which uses `HybridStorage` under the hood, while exposes sync and async APIs through `SyncStorage` and `AsyncStorage`.



All you need to do is to specify the configuration you want with `DiskConfig` and `MemoryConfig`. The default configurations are good to go, but you can customise a lot.



```swift

let diskConfig = DiskConfig(name: "Floppy")

let memoryConfig = MemoryConfig(expiry: .never, countLimit: 10, totalCostLimit: 10)



let storage = try? Storage(

  diskConfig: diskConfig,

  memoryConfig: memoryConfig,

  transformer: TransformerFactory.forCodable(ofType: User.self) // Storage

)

```



### Generic, Type safety and Transformer



All `Storage` now are generic by default, so you can get a type safety experience. Once you create a Storage, it has a type constraint that you don't need to specify type for each operation afterwards.



If you want to change the type, `Cache` offers `transform` functions, look for `Transformer` and `TransformerFactory` for built-in transformers.



```swift

let storage: Storage = ...

storage.setObject(superman, forKey: "user")



let imageStorage = storage.transformImage() // Storage

imageStorage.setObject(image, forKey: "image")



let stringStorage = storage.transformCodable(ofType: String.self) // Storage

stringStorage.setObject("hello world", forKey: "string")

```



Each transformation allows you to work with a specific type, however the underlying caching mechanism remains the same, you're working with the same `Storage`, just with different type annotation. You can also create different `Storage` for each type if you want.



`Transformer` is necessary because the need of serialising and deserialising objects to and from `Data` for disk persistency. `Cache` provides default `Transformer ` for `Data`, `Codable` and `UIImage/NSImage`



#### Codable types



`Storage` supports any objects that conform to [Codable](https://developer.apple.com/documentation/swift/codable) protocol. You can [make your own things conform to Codable](https://developer.apple.com/documentation/foundation/archives_and_serialization/encoding_and_decoding_custom_types) so that can be saved and loaded from `Storage`.



The supported types are



- Primitives like `Int`, `Float`, `String`, `Bool`, ...

- Array of primitives like `[Int]`, `[Float]`, `[Double]`, ...

- Set of primitives like `Set`, `Set`, ...

- Simply dictionary like `[String: Int]`, `[String: String]`, ...

- `Date`

- `URL`

- `Data`



#### Error handling



Error handling is done via `try catch`. `Storage` throws errors in terms of `StorageError`.



```swift

public enum StorageError: Error {

  /// Object can not be found

  case notFound

  /// Object is found, but casting to requested type failed

  case typeNotMatch

  /// The file attributes are malformed

  case malformedFileAttributes

  /// Can't perform Decode

  case decodingFailed

  /// Can't perform Encode

  case encodingFailed

  /// The storage has been deallocated

  case deallocated

  /// Fail to perform transformation to or from Data

  case transformerFail

}

```



There can be errors because of disk problem or type mismatch when loading from storage, so if want to handle errors, you need to do `try catch`



```swift

do {

  let storage = try Storage(diskConfig: diskConfig, memoryConfig: memoryConfig)

} catch {

  print(error)

}

```



### Configuration



Here is how you can play with many configuration options



```swift

let diskConfig = DiskConfig(

  // The name of disk storage, this will be used as folder name within directory

  name: "Floppy",

  // Expiry date that will be applied by default for every added object

  // if it's not overridden in the `setObject(forKey:expiry:)` method

  expiry: .date(Date().addingTimeInterval(2*3600)),

  // Maximum size of the disk cache storage (in bytes)

  maxSize: 10000,

  // Where to store the disk cache. If nil, it is placed in `cachesDirectory` directory.

  directory: try! FileManager.default.url(for: .documentDirectory, in: .userDomainMask,

    appropriateFor: nil, create: true).appendingPathComponent("MyPreferences"),

  // Data protection is used to store files in an encrypted format on disk and to decrypt them on demand

  protectionType: .complete

)

```



```swift

let memoryConfig = MemoryConfig(

  // Expiry date that will be applied by default for every added object

  // if it's not overridden in the `setObject(forKey:expiry:)` method

  expiry: .date(Date().addingTimeInterval(2*60)),

  /// The maximum number of objects in memory the cache should hold

  countLimit: 50,

  /// The maximum total cost that the cache can hold before it starts evicting objects

  totalCostLimit: 0

)

```



On iOS, tvOS we can also specify `protectionType` on `DiskConfig` to add a level of security to files stored on disk by your app in the app’s container. For more information, see [FileProtectionType](https://developer.apple.com/documentation/foundation/fileprotectiontype)



### Sync APIs



`Storage` is sync by default and is `thread safe`, you can access it from any queues. All Sync functions are constrained by `StorageAware` protocol.



```swift

// Save to storage

try? storage.setObject(10, forKey: "score")

try? storage.setObject("Oslo", forKey: "my favorite city", expiry: .never)

try? storage.setObject(["alert", "sounds", "badge"], forKey: "notifications")

try? storage.setObject(data, forKey: "a bunch of bytes")

try? storage.setObject(authorizeURL, forKey: "authorization URL")



// Load from storage

let score = try? storage.object(forKey: "score")

let favoriteCharacter = try? storage.object(forKey: "my favorite city")



// Check if an object exists

let hasFavoriteCharacter = try? storage.objectExists(forKey: "my favorite city")



// Remove an object in storage

try? storage.removeObject(forKey: "my favorite city")



// Remove all objects

try? storage.removeAll()



// Remove expired objects

try? storage.removeExpiredObjects()

```



#### Entry



There is time you want to get object together with its expiry information and meta data. You can use `Entry`



```swift

let entry = try? storage.entry(forKey: "my favorite city")

print(entry?.object)

print(entry?.expiry)

print(entry?.meta)

```



`meta` may contain file information if the object was fetched from disk storage.



#### Custom Codable



`Codable` works for simple dictionary like `[String: Int]`, `[String: String]`, ... It does not work for `[String: Any]` as `Any` is not `Codable` conformance, it will raise `fatal error` at runtime. So when you get json from backend responses, you need to convert that to your custom `Codable` objects and save to `Storage` instead.



```swift

struct User: Codable {

  let firstName: String

  let lastName: String

}



let user = User(fistName: "John", lastName: "Snow")

try? storage.setObject(user, forKey: "character")

```



### Async APIs



In `async` fashion, you deal with `Result` instead of `try catch` because the result is delivered at a later time, in order to not block the current calling queue. In the completion block, you either have `value` or `error`.



You access Async APIs via `storage.async`, it is also thread safe, and you can use Sync and Async APIs in any order you want. All Async functions are constrained by `AsyncStorageAware` protocol.



```swift

storage.async.setObject("Oslo", forKey: "my favorite city") { result in

  switch result {

    case .success:

      print("saved successfully")

    case .failure(let error):

      print(error)

  }

}



storage.async.object(forKey: "my favorite city") { result in

  switch result {

    case .success(let city):

      print("my favorite city is \(city)")

    case .failure(let error):

      print(error)

  }

}



storage.async.objectExists(forKey: "my favorite city") { result in

  if case .success(let exists) = result, exists {

    print("I have a favorite city")

  }

}



storage.async.removeAll() { result in

  switch result {

    case .success:

      print("removal completes")

    case .failure(let error):

      print(error)

  }

}



storage.async.removeExpiredObjects() { result in

  switch result {

    case .success:

      print("removal completes")

    case .failure(let error):

      print(error)

  }

}

```



#### Swift Concurrency



```swift

do {

  try await storage.async.setObject("Oslo", forKey: "my favorite city")

  print("saved successfully")

} catch {

  print(error)

}



do {

  let city = try await storage.async.object(forKey: "my favorite city")

  print("my favorite city is \(city)")

} catch {

  print(error)

}



do {

  let exists = try await storage.async.objectExists(forKey: "my favorite city")

  if exists {

    print("I have a favorite city")

  }

} catch {}



do {

  try await storage.async.remoeAll()

  print("removal completes")

} catch {

  print(error)

}



do {

  try await storage.async.removeExpiredObjects()

  print("removal completes")

} catch {

  print(error)

}

```



### Expiry date



By default, all saved objects have the same expiry as the expiry you specify in `DiskConfig` or `MemoryConfig`. You can overwrite this for a specific object by specifying `expiry` for `setObject`



```swift

// Default expiry date from configuration will be applied to the item

try? storage.setObject("This is a string", forKey: "string")



// A given expiry date will be applied to the item

try? storage.setObject(

  "This is a string",

  forKey: "string",

  expiry: .date(Date().addingTimeInterval(2 * 3600))

)



// Clear expired objects

storage.removeExpiredObjects()

```



## Observations



[Storage](#storage) allows you to observe changes in the cache layer, both on

a store and a key levels. The API lets you pass any object as an observer,

while also passing an observation closure. The observation closure will be

removed automatically when the weakly captured observer has been deallocated.



## Storage observations



```swift

// Add observer

let token = storage.addStorageObserver(self) { observer, storage, change in

  switch change {

  case .add(let key):

    print("Added \(key)")

  case .remove(let key):

    print("Removed \(key)")

  case .removeAll:

    print("Removed all")

  case .removeExpired:

    print("Removed expired")

  }

}



// Remove observer

token.cancel()



// Remove all observers

storage.removeAllStorageObservers()

```



## Key observations



```swift

let key = "user1"



let token = storage.addObserver(self, forKey: key) { observer, storage, change in

  switch change {

  case .edit(let before, let after):

    print("Changed object for \(key) from \(String(describing: before)) to \(after)")

  case .remove:

    print("Removed \(key)")

  }

}



// Remove observer by token

token.cancel()



// Remove observer for key

storage.removeObserver(forKey: key)



// Remove all observers

storage.removeAllKeyObservers()

```



## Handling JSON response



Most of the time, our use case is to fetch some json from backend, display it while saving the json to storage for future uses. If you're using libraries like [Alamofire](https://github.com/Alamofire/Alamofire) or [Malibu](https://github.com/hyperoslo/Malibu), you mostly get json in the form of dictionary, string, or data.



`Storage` can persist `String` or `Data`. You can even save json to `Storage` using `JSONArrayWrapper` and `JSONDictionaryWrapper`, but we prefer persisting the strong typed objects, since those are the objects that you will use to display in UI. Furthermore, if the json data can't be converted to strongly typed objects, what's the point of saving it ? 😉



You can use these extensions on `JSONDecoder` to decode json dictionary, string or data to objects.



```swift

let user = JSONDecoder.decode(jsonString, to: User.self)

let cities = JSONDecoder.decode(jsonDictionary, to: [City].self)

let dragons = JSONDecoder.decode(jsonData, to: [Dragon].self)

```



This is how you perform object converting and saving with `Alamofire`



```swift

Alamofire.request("https://gameofthrones.org/mostFavoriteCharacter").responseString { response in

  do {

    let user = try JSONDecoder.decode(response.result.success, to: User.self)

    try storage.setObject(user, forKey: "most favorite character")

  } catch {

    print(error)

  }

}

```



## What about images



If you want to load image into `UIImageView` or `NSImageView`, then we also have a nice gift for you. It's called [Imaginary](https://github.com/hyperoslo/Imaginary) and uses `Cache` under the hood to make your life easier when it comes to working with remote images.



## Installation



### Cocoapods



**Cache** is available through [CocoaPods](http://cocoapods.org). To install

it or update it, use the following line to your Podfile:



```ruby

pod 'Cache', :git => 'https://github.com/hyperoslo/Cache.git'



```



### Carthage



**Cache** is also available through [Carthage](https://github.com/Carthage/Carthage).

To install just write into your Cartfile:



```ruby

github "hyperoslo/Cache"

```



You also need to add `SwiftHash.framework` in your [copy-frameworks](https://github.com/Carthage/Carthage#if-youre-building-for-ios-tvos-or-watchos) script.



## Author



- [Hyper](http://hyper.no) made this with ❤️

- Inline MD5 implementation from [SwiftHash](https://github.com/onmyway133/SwiftHash)



## Contributing



We would love you to contribute to **Cache**, check the [CONTRIBUTING](https://github.com/hyperoslo/Cache/blob/master/CONTRIBUTING.md) file for more info.



## License



**Cache** is available under the MIT license. See the [LICENSE](https://github.com/hyperoslo/Cache/blob/master/LICENSE.md) file for more info.