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@kean kean released this Jul 8, 2019 · 102 commits to master since this release

Nuke 8 is the most powerful, performant, and refined release yet. It contains major advancements it some areas and brings some great new features.

Cache processed images on disk · New built-in image processors · ImagePipeline v2 · Up to 30% faster main thread performance · Result type · Improved deduplication · os_signpost integration · Refined ImageRequest API · Smart decompression · Entirely new documentation

Most of the Nuke APIs are source compatible with Nuke 7. There is also a Nuke 8 Migration Guide to help with migration.

Image Processing

#227 Cache Processed Images on Disk

ImagePipeline now supports caching of processed images on disk. To enable this feature set isDataCacheForProcessedDataEnabled to true in the pipeline configuration and provide a dataCache. You can use a built-in DataCache introduced in Nuke 7.3 or write a custom one.

Image cache can significantly improve the user experience in the apps that use heavy image processors like Gaussian Blur.

#243 New Image Processors

Nuke now ships with a bunch of built-in image processors including:

  • ImageProcessor.Resize
  • ImageProcessor.RoundedCorners
  • ImageProcessor.Circle
  • ImageProcessor.GaussianBlur
  • ImageProcessor.CoreImageFilter

There are also ImageProcessor.Anonymous to create one-off processors from closures and ImageProcessor.Composition to combine two or more processors.

#245 Simplified Processing API

Previously Nuke offered multiple different ways to add processors to the request. Now there is only one, which is also better than all of the previous versions:

let request = ImageRequest(
    url: URL(string: "http://..."),
    processors: [
        ImageProcessor.Resize(size: CGSize(width: 44, height: 44), crop: true),
        ImageProcessor.RoundedCorners(radius: 16)
    ]
)

Processors can also be set using a respective mutable processors property.

Notice that AnyImageProcessor is gone! You can simply use ImageProcessing protocol directly in places where previously you had to use a type-erased version.

#229 Smart Decompression

In the previous versions, decompression was part of the processing API and ImageDecompressor was the default processor set for each image request. This was mostly done to simplify implementation but it was confusing for the users.

In the new version, decompression runs automatically and it no longer a "processor". The new decompression is also smarter. It runs only when needed – when we know that image is still in a compressed format and wasn't decompressed by one of the image processors.

Decompression runs on a new separate imageDecompressingQueue. To disable decompression you can set a new isDecompressionEnabled pipeline configuration option to false.

#247 Avoiding Duplicated Work when Applying Processors

The pipeline avoids doing any duplicated work when loading images. Now it also avoids applying the same processors more than once. For example, let's take these two requests:

let url = URL(string: "http://example.com/image")
pipeline.loadImage(with: ImageRequest(url: url, processors: [
    ImageProcessor.Resize(size: CGSize(width: 44, height: 44)),
    ImageProcessor.GaussianBlur(radius: 8)
]))
pipeline.loadImage(with: ImageRequest(url: url, processors: [
    ImageProcessor.Resize(size: CGSize(width: 44, height: 44))
]))

Nuke will load the image data only once, resize the image once and apply the blur also only once. There is no duplicated work done at any stage. If any of the intermediate results are available in the data cache, they will be used.

ImagePipeline v2

Nuke 8 introduced a major new iteration of the ImagePipeline class. The class was introduced in Nuke 7 and it contained a lot of incidental complexity due to addition of progressive decoding and some other new features. In Nuke 8 it was rewritten to fully embrace progressive decoding. The new pipeline is smaller, simpler, easier to maintain, and more reliable.

It is also faster.

+30% Main Thread Performance

The image pipeline spends even less time on the main thread than any of the previous versions. It's up to 30% faster than Nuke 7.

#239 Load Image Data

Add a new ImagePipeline method to fetch original image data:

@discardableResult
public func loadData(with request: ImageRequest,
                     progress: ((_ completed: Int64, _ total: Int64) -> Void)? = nil,
                     completion: @escaping (Result<(data: Data, response: URLResponse?), ImagePipeline.Error>) -> Void) -> ImageTask

This method now powers ImagePreheater with destination .diskCache introduced in Nuke 7.4 (previously it was powered by a hacky internal API).

#245 Improved ImageRequest API

The rarely used options were extracted into the new ImageRequestOptions struct and the request initializer can now be used to customize all of the request parameters.

#255 filteredURL

You can now provide a filteredURL to be used as a key for caching in case the URL contains transient query parameters:

let request = ImageRequest(
    url: URL(string: "http://example.com/image.jpeg?token=123")!,
    options: ImageRequestOptions(
        filteredURL: "http://example.com/image.jpeg"
    )
)

#241 Adopt Result type

Adopt the Result type introduced in Swift 5. So instead of having a separate response and error parameters, the completion closure now has only one parameter - result.

public typealias Completion = (_ result: Result<ImageResponse, ImagePipeline.Error>) -> Void

Performance

Apart from the general performance improvements Nuke now also offers a great way to measure performance and gain visiblity into how the system behaves when loading images.

#250 Integrate os_signpost

Integrate os_signpost logs for measuring performance. To enable the logs set ImagePipeline.Configuration.isSignpostLoggingEnabled (static property) to true before accessing the shared pipeline.

With these logs, you have visibility into the image pipeline. For more information see WWDC 2018: Measuring Performance Using Logging which explains os_signpost in a great detail.

Screenshot 2019-06-01 at 10 46 52

Documentation

All the documentation for Nuke was rewritten from scratch in Nuke 8. It's now more concise, clear, and it even features some fantastic illustrations:

Screenshot 2019-06-11 at 22 31 18

The screenshots come the the reworked demo project. It gained new demos including Image Processing demo and also a way to change ImagePipeline configuration in runtime.

Misc

  • Add a cleaner way to set ImageTask priority using a new priority property – #251
  • [macOS] Implement image cost calculation for ImageCache#236
  • [watchOS] Add WKInterfaceImage support
  • Future-proof Objective-C ImageDisplaying protocol by adding nuke_ prefixes to avoid clashes in Objective-C runtime
  • Add convenience func decode(data: Data) -> Image? method with a default isFinal argument to ImageDecoding protocol – e3ca5e
  • Add convenience func process(image: Image) -> Image? method to ImageProcessing protocol
  • DataCache will now automatically re-create its root directory if it was deleted underneath it
  • Add public flush method to DataCache
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