How to cache data using NSCache in swift

Store Image in cache in swift

Most apps have pictures or graphics that they show to users. App developers often have to download and display these images, which can be a lot of work. Sometimes, the app might end up loading the same picture again and again, which is a waste of time and energy.

This article will teach you how to make your app run better by creating something called an Image Cache and connecting it with the Image Loader using a framework called Combine.

Store Image in cache in swift

Using NSCache as a storage

When you’re making an iPhone or iPad app and you want to store information so it can be quickly retrieved later, you might think about using something called NSCache. There are good things about NSCache, like it can be used safely with different parts of the app and it can get rid of stuff when memory is running low. But there are also some downsides, like it’s not always clear which things will get removed from the cache.

NSCache is usually a better choice for caching than other storage options available in Swift or Foundation frameworks. This article will show you how to use NSCache to store images in your app. Of course, you can always choose another option as long as it follows the rules for replacing cached data.

If your app shows pictures that it gets from the internet, it might run slowly and make it hard for people to use. For instance, when someone scrolls through a list of pictures, the app might start to stutter and not respond smoothly. This happens because the app doesn’t load the whole picture at once when it’s supposed to be shown on the screen. Instead, there are several steps that need to happen first, and that can make the app slow down.

  • loading — loads compressed image into memory;
  • decoding — converts encoded image data into per pixel image information;
  • rendering — copies and scales the image data from the image buffer into the frame buffer.

All of those image loading steps can take up a lot of time, especially when they’re happening on the main part of the app. This can cause the app to slow down and not respond as quickly as people would like. There are a few ways you could make the app faster, such as doing some of the work ahead of time. For example, you could decode and render an image before it’s even shown in the app, which would make things move more smoothly.

This is a function that takes a normal image and turns it into a decompressed and ready-to-use version. It’s a good idea to store these decompressed images in a cache so they can be quickly accessed later. This will help make the app display pictures faster and more smoothly, but it might take up some extra storage space on the device.

Here’s an example code showing how to use NSCache in Swift:

let cache = NSCache<NSString, UIImage>()

// Add an image to the cache
let image = UIImage(named: "example.jpg")
cache.setObject(image!, forKey: "example")

// Retrieve an image from the cache
if let cachedImage = cache.object(forKey: "example") {
    // Use the cached image
} else {
    // Image not found in cache

// Remove an object from the cache
cache.removeObject(forKey: "example")

// Set the maximum number of objects the cache can hold
cache.countLimit = 100

In this example, we create an NSCache object that can hold UIImage objects with NSString keys. We then add an image to the cache using the setObject(_:forKey:) method, retrieve the image using the object(forKey:) method, remove the image using the removeObject(forKey:) method, and set the maximum number of objects the cache can hold using the countLimit property.

NSCache is a useful tool for optimizing app performance and reducing memory usage by caching temporary objects in memory. However, it’s important to use NSCache judiciously to prevent excessive memory usage and potential crashes.

  1. Understanding NSCache and Its Benefits
  • What is NSCache and how does it work?
  • Why should you use NSCache instead of traditional data structures?
  • Key benefits of NSCache for Swift development.
  1. Implementing NSCache in Swift
  • Step-by-step guide to incorporating NSCache in your Swift projects.
  • How to set and retrieve values from the cache.
  • Fine-tuning the behavior of NSCache using its properties and methods.
  1. Leveraging NSCache for Performance Optimization
  • Boosting your app’s responsiveness by caching expensive or time-consuming operations.
  • Caching network responses and API data for offline usage.
  • Improving user experience through smoother transitions and faster content loading.
  1. Handling Cache Eviction and Memory Management
  • Understanding cache eviction policies and their impact on performance.
  • Strategies for handling memory warnings and cache flushing.
  • Best practices for managing NSCache to prevent memory leaks.
  1. Advanced NSCache Techniques and Use Cases
  • Using NSCache as a thread-safe storage solution.
  • Integrating NSCache with other caching mechanisms, such as disk-based caching.
  • Real-world examples showcasing NSCache’s versatility in various app scenarios.

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NSCache Source Code

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