NSKeyedArchiver适合将UIImage转换为Data吗？
do {
let data = try NSKeyedArchiver.archivedData(withRootObject: UIImage(named: somePath), requiringSecureCoding: true)
...
} catch {
print(error)
}
还是使用pngData()更为合适，否则是否有些过头了？
let image = UIImage(named: somePath)
let data = image?.pngData()
我该如何将UIImage转换为HEIF/HEIC Data？
目的是将图像保存到设备的文件系统中。
不要使用NSKeyedArchiver将您的图像转换为数据。选择图像格式（HEIC，PNG，JPEG等）并获取其数据表示形式。仅在保存用于UI的图像时才应使用PNG。大多数情况下，jpeg是首选。如果设备支持HEIC，则可以考虑其图像质量和减小的数据大小。
如果您需要检查用户设备是否支持HEIC类型，则可以按以下步骤操作：
var isHeicSupported: Bool {
(CGImageDestinationCopyTypeIdentifiers() as! [String]).contains("public.heic")
}
如果您需要将图像转换为HEIC格式，则需要从UIImage获取CGImage并将UIImage的imageOrientation转换为CGImagePropertyOrientation以在创建其数据表示时保留方向：
extension UIImage {
var heic: Data? { heic() }
func heic(compressionQuality: CGFloat = 1) -> Data? {
guard
let mutableData = CFDataCreateMutable(nil, 0),
let destination = CGImageDestinationCreateWithData(mutableData, "public.heic" as CFString, 1, nil),
let cgImage = cgImage
else { return nil }
CGImageDestinationAddImage(destination, cgImage, [kCGImageDestinationLossyCompressionQuality: compressionQuality, kCGImagePropertyOrientation: cgImageOrientation.rawValue] as CFDictionary)
guard CGImageDestinationFinalize(destination) else { return nil }
return mutableData as Data
}
}
extension CGImagePropertyOrientation {
init(_ uiOrientation: UIImage.Orientation) {
switch uiOrientation {
case .up: self = .up
case .upMirrored: self = .upMirrored
case .down: self = .down
case .downMirrored: self = .downMirrored
case .left: self = .left
case .leftMirrored: self = .leftMirrored
case .right: self = .right
case .rightMirrored: self = .rightMirrored
@unknown default:
fatalError()
}
}
}
extension UIImage {
var cgImageOrientation: CGImagePropertyOrientation { .init(imageOrientation) }
}
无损压缩的用法：
if isHeicSupported, let heicData = image.heic {
// write your heic image data to disk
}
或者给您的图像添加压缩：
if isHeicSupported, let heicData = image.heic(compressionQuality: 0.75) {
// write your compressed heic image data to disk
}
UIImage或使用具有属性的结构体包装图像，那么推荐的数据序列化是什么？ - lurning too koad