There are several commonly used picture formats.

  • PNG
  • JPEG
  • GIF
  • WebP is a Google-made image format optimized for fast delivery over the Web
  • TIFF/TIF has been widely used in digital impact, remote sensing, medicine and other fields. TIFF files have a.tif or.tiff suffix
  • HEIC iOS11 after apple take pictures of the default format
  • HEIF is used to store moving images

So, how to judge. Image format usually stored images of Hex Signature in the Signature (hexadecimal) believe that address can refer to: www.garykessler.net/library/fil…

The first two bytes of JPGE binary data are
Hex Signature
FF D8
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PNG
Hex Signature
89 50 4E 47 0D 0A 1A 0A
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GIF
Hex Signature
47 49 46 38 37 61 or
47 49 46 38 39 61
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TIFF
Hex Signature
49 20 49 or
49 49 2A 00 or
4D 4D 00 2B or
4D 4D 00 2A
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HEIC
Hex Signature
00
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HEIF
Hex Signature
00
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A lot of people on the Internet are copied, they know what the code looks like. But I don’t know why it is necessary to determine information such as HEIC, HEIX, mIF1, etc. It was later found here. file-extension.net/seeker/

WEBP
Hex Signature
52
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Why is Webp truncated from 0 to 12? What is the basis of the conversion to ASCII?

You can find it in Google’s official introduction. The header file size is 12Bytes

ASCII
RIFF
WEBP
Developers.google.com/speed/webp/…

Once you understand the principle, it’s code!

enum ImageFormat {
    case Unknow
    case JPEG
    case PNG
    case GIF
    case TIFF
    case WebP
    case HEIC
    case HEIF
}
extension Data {
    func getImageFormat() -> ImageFormat  {
        var buffer = [UInt8](repeating: 0, count: 1)
        self.copyBytes(to: &buffer, count: 1)
        
        switch buffer {
        case [0xFF]: return .JPEG
        case [0x89]: return .PNG
        case [0x47]: return .GIF
        case [0x49],[0x4D]: return .TIFF
        case [0x52] where self.count >= 12:
            if let str = String(data: self[0...11], encoding: .ascii), str.hasPrefix("RIFF"), str.hasSuffix("WEBP") {
                return .WebP
            }
        case [0x00] where self.count >= 12:
            if let str = String(data: self[8...11], encoding: .ascii) {
                let HEICBitMaps = Set(["heic", "heis", "heix", "hevc", "hevx"])
                if HEICBitMaps.contains(str) {
                    return .HEIC
                }
                let HEIFBitMaps = Set(["mif1", "msf1"])
                if HEIFBitMaps.contains(str) {
                    return .HEIF
                }
            }
        default: break;
        }
        return .Unknow
    }
}
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