A Swift cache handler

CacheHandler is a simple Swift package to handle a cache in your app. It uses NSCache as a storage but let you store structs objects. You can choose its key type (a class), its cache duration and expired cache policy (see below).

I've developed CacheHandler for my own usage as I needed to cache weather states from WeatherKit. I thought it might be useful for few of you.

Usage

Installation

Add CacheHandler package to your project.

In Xcode: File -> Add Packages... then enter my project GitHub URL:
https://github.com/Jonathan-Gander/CacheHandler

Import module

In file you want to use the cache handler:

import CacheHandler

Create CacheHandler

Create your cache handler with a class used as a key and one as stored object. Stored objects can be class or struct.

As an example, let's say I have a MyObject struct that I want to store. And I will use a NSString as key.

struct MyObject {
    let name: String
    let age: Int
}

let cacheHandler = CacheHandler<NSString, MyObject>()

CacheHandler init takes two optional parameters:

• cacheDuration: (in seconds) Set how long an object can stay in the cache. After this duration, object will be removed from cache next time you try to get it.
• expiredCachePolicy: If you try to get an object that is expired (= it is in cache for more than cacheDuration seconds), you can choose if you get the object or if you get nil.

By default, cacheDuration is 3600 seconds (1 hour) and expiredCachePolicy is set to .ReturnNil to return a nil instead of object.

To change this, simply call init like this:

let cacheHandler = CacheHandler<NSString, MyObject>(cacheDuration: 60, expiredCachePolicy: .ReturnObject) // cache of 60 seconds only

Store an object

To store an object in your CacheHandler, simply call addObject function:

let object = MyObject(name: "Marvin", age: 42)
cacheHandler.addObject(object, withKey: "obj1")

Get an object

To get an object from your CacheHandler, simply call "getObject` function:

let object: MyObject? = cacheHandler.getObject(withKey: "obj1")

You can get the object if it is in cache and its cache duration is less or equal to cacheDuration seconds. Or if it is in cache, its cache duration is greater than cacheDuration seconds and expiredCachePolicy is set to .ReturnObject. In other cases, you get a nil.

Licence

Be free to use my CacheHandler Package in your app. Licence is available here. Please only add a copyright and licence notice.