Johnny is a caching library written in Swift 3.

Features

• [x] Generic cache with out-of-the-box support for
  • String, Bool, Int, UInt, Int64, UInt64, Float, Double
  • URL, Data, Date
  • UIImage, UIColor
  • Arrays, Dictionaries and Sets of the above
  • Optionals of the above
  • Any type that conforms to the Storable protocol

• [x] Multiplatform, supporting iOS, macOS, tvOS & watchOS
• [x] First-level memory cache using NSCache
• [x] Second-level LRU disk cache
• [x] Disk access in background thread (always when saving, optionally when fetching)
• [x] Syncronous & Asynchronous API support
• [x] Automatic cache eviction on memory warnings & disk capacity reached
• [x] Unit tested
• [x] Concise, well-structured code to encourage contributions

Extra ❤️ for images:

• [x] func setImageWithURL extension on UIImageView, UIButton & NSImageView, optimized for cell reuse

Usage

Caching

Johnny.cache(Date(), key: "FirstStart")

Retrieving

// The type of the retrived value must be explicitly stated for the compiler.
let date: Date? = Johnny.pull("FirstStart")

Async fetch

If you know you are retrieving a large object (> 1.5 MB):

Johnny.pull("4KImage") { (value: UIImage?) in

}

Prefix

You can set a global prefix that gets attached to the key parameter in every call to enable for example caching of data on a per userID basis.

Johnny.prefix = localUser.userID

Examples

Storable

Note, that since the protocol uses a static constructor function instead of an initializer, you can extend any class without errors, even if you don’t have access to its source (like Standard library classes)

public protocol Storable {
    associatedtype Result
    static func fromData(data: NSData) -> Result?
    func toData() -> NSData
}

Collections

You can cache any collection of items conforming to the Storable protocol (most Stdlib data types already do)

let array: [String] = ["Folsom", "Prison", "Blues"]
let stringSet: Set<String> = ["I've", "been", "everywhere"]
// In case of dictionaries, the value must explicitly conform to Storable (so [String: AnyObject] does not work, while [String: Double] does)
let dictionary: [String: String] = ["first": "Solitary", "second": "man"]

Johnny.cache(array, key: "folsom")
Johnny.cache(stringSet, key: "everywhere")
Johnny.cache(dictionary, key: "solitary")

Custom types

Due to current Swift limitations, since the Storable protocol has an associatedType, conformance must be added through an extension. class User: Storable will not work.

class User {

    enum Badassery: String { case Total }

    var name: String? = "Johnny"
    var uid: Int = 84823682
    var badassery = Badassery.Total
}


extension User: Storable {
typealias Result = User

static func fromData(data: NSData) -> User.Result? {
    let dict = try! NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions()) as! [NSObject: AnyObject]

    let user = User()
    user.uid = dict["identification"] as! Int
    user.name = dict["name"] as? String
    user.badassery = Badassery(rawValue: dict["badassery"] as! String)!
    return user
}

func toData() -> NSData {
    let json = ["identification": uid, "name": name, "badasery": badassery.rawValue]
    return try! NSJSONSerialization.dataWithJSONObject(json, options: NSJSONWritingOptions())
    }
}

Using it with Johnny:

let johnny: User = User()
Johnny.cache(johnny, key: "John")
let cachedJohn: User = Johnny.pull("John")

Requirements

• iOS 8.0+
• macOS 10.10+
• tvOS 9.0+
• watchOS 2.0+
• Swift 2.0+ (there’s also a swift3 branch)

Install

CocoaPods

pod 'Johnny'

Attribution

I’d like to thank the creators of Pantry and Haneke as those projects provided much of the inspiration and some code. Johnny was dreamed up to be the best of both worlds.

License

Johnny is released under the MIT license. See LICENSE for details.