将 Gif 图像转换为 NSData

Question

我的相册中有一张 gif 图像。当我使用UIImagePickerController 选择该图像时，我需要将图像转换为NSData 进行存储。

之前我用过

NSData *thumbData = UIImageJPEGRepresentation(thumbnail, 0.5);

但它不适用于 gif 图像。 thumbData 将为零。

1. 如何从 gif 图像中获取 NSData？

2. 我怎么知道是gif图片需要特殊处理？

Answer 1

这里的关键是将 GIF 文件或 URL 下载直接保存到 NSData 中，而不是使其成为 UIImage。绕过 UIImage 会让 GIF 文件保留动画。

下面是一些将 GIF 文件转换为 NSData 的代码：

NSString *filePath = [[NSBundle mainBundle] pathForResource: @"gifFileName" ofType: @"gif"];

NSData *gifData = [NSData dataWithContentsOfFile: filePath];

但老实说，您真的应该考虑完全不使用 GIF。

Answer 2

斯威夫特

Gif 必须不在资产中。

let path = Bundle.main.path(forResource: "loader", ofType: "gif")!
let data = try! Data(contentsOf: URL(fileURLWithPath: path))
return data

Answer 3

https://github.com/mattt/AnimatedGIFImageSerialization

UIImage *image = ...;
NSData *data = [AnimatedGIFImageSerialization animatedGIFDataWithImage:image
                                                              duration:1.0
                                                             loopCount:1
                                                                 error:nil];

Answer 4

转换 .GIF 文件的代码可以在 NSdata 中转换 -

NSString *pathForFile = [[NSBundle mainBundle] pathForResource: @"myGif" ofType: @"gif"];

NSData *dataOfGif = [NSData dataWithContentsOfFile: pathForFile];

NSLog(@"Data: %@", dataOfGif);

Answer 5

1. 那些正在寻找这个问题的快速答案的人，这里有一个 UIImage 的扩展来完成这项工作。

import UIKit
import MobileCoreServices

extension UIImage {
    func UIImageAnimatedGIFRepresentation(gifDuration: TimeInterval = 0.0, loopCount: Int = 0) throws -> Data {
        let images = self.images ?? [self]
        let frameCount = images.count
        let frameDuration: TimeInterval = gifDuration <= 0.0 ? self.duration / Double(frameCount) : gifDuration / Double(frameCount)
        let frameDelayCentiseconds = Int(lrint(frameDuration * 100))
        let frameProperties = [
            kCGImagePropertyGIFDictionary: [
                kCGImagePropertyGIFDelayTime: NSNumber(value: frameDelayCentiseconds)
            ]
        ]

        guard let mutableData = CFDataCreateMutable(nil, 0),
           let destination = CGImageDestinationCreateWithData(mutableData, kUTTypeGIF, frameCount, nil) else {
            throw NSError(domain: "AnimatedGIFSerializationErrorDomain",
                          code: -1,
                          userInfo: [NSLocalizedDescriptionKey: "Could not create destination with data."])
        }
        let imageProperties = [
            kCGImagePropertyGIFDictionary: [kCGImagePropertyGIFLoopCount: NSNumber(value: loopCount)]
        ] as CFDictionary
        CGImageDestinationSetProperties(destination, imageProperties)
        for image in images {
            if let cgimage = image.cgImage {
                CGImageDestinationAddImage(destination, cgimage, frameProperties as CFDictionary)
            }
        }

        let success = CGImageDestinationFinalize(destination)
        if !success {
            throw NSError(domain: "AnimatedGIFSerializationErrorDomain",
                          code: -2,
                          userInfo: [NSLocalizedDescriptionKey: "Could not finalize image destination"])
        }
        return mutableData as Data
    }
}

1. 虽然上述扩展可以完成这项工作，但从图像选择器处理 gif 更为简单，下面是 UIImagePickerControllerDelegate 函数中的实现。

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
    let info = Dictionary(uniqueKeysWithValues: info.map {key, value in (key.rawValue, value)})
    if let url = info[UIImagePickerController.InfoKey.referenceURL.rawValue] as? URL, url.pathExtension.lowercased() == "gif" {
       picker.dismiss(animated: false, completion: nil)
       url.getGifImageDataFromAssetUrl(completion: { imageData in
           // Use imageData here.
       })
       return
    }
}

在 URL 中使用扩展功能

import UIKit
import Photos

extension URL {
    func getGifImageDataFromAssetUrl(completion: @escaping(_ imageData: Data?) -> Void) {
        let asset = PHAsset.fetchAssets(withALAssetURLs: [self], options: nil)
        if let image = asset.firstObject {
            PHImageManager.default().requestImageData(for: image, options: nil) { (imageData, _, _, _) in
                completion(imageData)
            }
        }
    }
}