EXIF数据读写

Question

我搜索了从图片文件中获取 EXIF 数据并将其写回 Swift 的方法。但我只能找到不同语言的预定义库。

我还找到了对“CFDictionaryGetValue”的引用，但是我需要哪些键来获取数据？我该如何写回它？

Answer 1

我用它来获取图像文件中的EXIF信息：

import ImageIO

let fileURL = theURLToTheImageFile
if let imageSource = CGImageSourceCreateWithURL(fileURL as CFURL, nil) {
    let imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, nil)
    if let dict = imageProperties as? [String: Any] {
        print(dict)
    }
}

它为您提供了一本包含各种信息（例如颜色配置文件）的字典 - EXIF 信息具体位于

dict["{Exif}"]

。

Answer 2

斯威夫特4

extension UIImage {
    func getExifData() -> CFDictionary? {
        var exifData: CFDictionary? = nil
        if let data = self.jpegData(compressionQuality: 1.0) {
            data.withUnsafeBytes {(bytes: UnsafePointer<UInt8>)->Void in
                if let cfData = CFDataCreate(kCFAllocatorDefault, bytes, data.count) {
                    let source = CGImageSourceCreateWithData(cfData, nil)
                    exifData = CGImageSourceCopyPropertiesAtIndex(source!, 0, nil)
                }
            }
        }
        return exifData
    }
}

斯威夫特5

extension UIImage {

    func getExifData() -> CFDictionary? {
        var exifData: CFDictionary? = nil
        if let data = self.jpegData(compressionQuality: 1.0) {
            data.withUnsafeBytes {
                let bytes = $0.baseAddress?.assumingMemoryBound(to: UInt8.self)
                if let cfData = CFDataCreate(kCFAllocatorDefault, bytes, data.count), 
                    let source = CGImageSourceCreateWithData(cfData, nil) {
                    exifData = CGImageSourceCopyPropertiesAtIndex(source, 0, nil)
                }
            }
        }
        return exifData
    }
}

Answer 3

您可以使用 AVAssetExportSession 写入元数据。

let asset = AVAsset(url: existingUrl)
let exportSession = AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetHighestQuality)
exportSession?.outputURL = newURL
exportSession?.metadata = [
  // whatever [AVMetadataItem] you want to write
]
exportSession?.exportAsynchronously {
  // respond to file writing completion
}

Answer 4

我使用这种方法：

extension Data { // for UIImage.data only

    var metadata: [AnyHashable : Any]? {
        let options = [kCGImageDestinationLossyCompressionQuality : NSNumber(value: 1),
                                         kCGImagePropertyHasAlpha : kCFBooleanTrue,
                                        kCGImageSourceShouldCache : kCFBooleanFalse] as CFDictionary
        guard let source = CGImageSourceCreateWithData(self as CFData, options) else { return nil }
        return CGImageSourceCopyPropertiesAtIndex(source, 0, options) as? [AnyHashable: Any]
    }
}

任何

image

都可以将其用作

    guard let data = image.jpegData(compressionQuality: 1),
          var metadata = data.metadata
    else {
        return nil
    }
    EXIF -> metadata[kCGImagePropertyExifDictionary] as? [AnyHashable : Any] 
    TIFF -> metadata[kCGImagePropertyTIFFDictionary] as? [AnyHashable : Any]
    GPS -> metadata[kCGImagePropertyGPSDictionary] as? [AnyHashable : Any]
    & etc. 

用这个多变的字典做任何你想做的事。