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ImageCache allows you to cache an image from an HTTP request. You can alternatively use a plugin that auto handles image caching like @triniwiz/nativescript-image-cache-it.

Using ImageCache

For consistency, you should use a single ImageCache instance throughout your app.

ts
import { ImageCache } from '@nativescript/core'

const imageCache = new ImageCache()

Save an image to cache

To retrieve an image from a remote server and cache it, use either the push or enqueue method. These methods cache the android.graphics.Bitmap (Android) or UIImage (iOS) instance.

ts
imageCache.enqueue({
  url: this.url,
  key: 'cat',
  completed(image: android.graphics.Bitmap | UIImage, key) {
    console.log('Successfully retrived and cached the cat image')
  },
  error(key) {
    console.log('cache error')
  },
})

Note

To call the push method instead, just replace enqueue with push

Getting an image from cache

To get an image from the cache, use the get method.

ts
const cachedImage = imageCache.get('cat')

API

constructor

ts
const imageCache = new ImageCache()

Creates an ImageCache instance.


placeholder

ts
imageCache.placeholder = imageSource

The image to be used to notify for a pending download request - e.g. loading indicator.


maxRequests

ts
imageCache.number = 2

The maximum number of simultaneous download requests. Defaults to 5


push

ts
imageCache.push(request)

Adds a new image to the start of the cache. request is an object with the following members:

  • url(string): The url of the image.
  • key(string): The name to uniquely identify the image in the cache.
  • Optional: completed is a function to be called upon caching an image successfully.
  • Optional: error is a function to be called when error has occured during caching.

enqueue

ts
imageCache.enqueue(request)

Adds a new image to the end of the cache. For more details about the request parameter, see the push() method.


get

ts
imageCache.get(key)

Gets the image with a given key from the cache, or undefined if it's not in the cache.

remove

ts
imageCache.remove(imageKey)

Remove the specified image from the cache.


clear

ts
imageCache.clear()

Clears all the images from the cache.


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