Bild-Datei-Typ programmgesteuert in swift

Haben Sie, um das erste byte des Bildes in binäre. Dieses byte geben die Art des Bildes Art. Hier ist der code, den ich verwendet habe für mein Projekt aber in Objective-c:

uint8_t c;
        [_receivedData getBytes:&c length:1];

        NSString *extension = @"jpg";

        switch (c) {
            case 0xFF:
            {
                extension = @"jpg";
            }
            case 0x89:
            {
                extension = @"png";
            }
                break;
            case 0x47:
            {
                extension = @"gif";
            }
                break;
            case 0x49:
            case 0x4D:
            {
                extension = @"tiff";
            }
                break;
            default:
                FLog(@"unknown image type");
        }

Versuchen Sie es mit diesem in swift (1.2, sonst haben Sie zu verwenden var ext):

func imageType(imgData : NSData) -> String
{
    var c = [UInt8](count: 1, repeatedValue: 0)
    imgData.getBytes(&c, length: 1)

    let ext : String

    switch (c[0]) {
    case 0xFF:

        ext = "jpg"

    case 0x89:

        ext = "png"
    case 0x47:

        ext = "gif"
    case 0x49, 0x4D :
        ext = "tiff"
    default:
        ext = "" //unknown
    }

    return ext
}

Können Sie testen im Projekt https://github.com/bonyadmitr/ImageFormat

Zum Projekt hinzufügen

import Foundation

///can be done "heic", "heix", "hevc", "hevx"
enum ImageFormat: String {
    case png, jpg, gif, tiff, webp, heic, unknown
}

extension ImageFormat {
    static func get(from data: Data) -> ImageFormat {
        switch data[0] {
        case 0x89:
            return .png
        case 0xFF:
            return .jpg
        case 0x47:
            return .gif 
        case 0x49, 0x4D:
            return .tiff 
        case 0x52 where data.count >= 12:
            let subdata = data[0...11]

            if let dataString = String(data: subdata, encoding: .ascii),
                dataString.hasPrefix("RIFF"),
                dataString.hasSuffix("WEBP")
            {    
                return .webp
            }

        case 0x00 where data.count >= 12 :
            let subdata = data[8...11]

            if let dataString = String(data: subdata, encoding: .ascii),
                Set(["heic", "heix", "hevc", "hevx"]).contains(dataString)
                ///OLD: "ftypheic", "ftypheix", "ftyphevc", "ftyphevx"
            {    
                return .heic
            }
        default:
            break
        }
        return .unknown
    } 

    var contentType: String {
        return "image/\(rawValue)"
    }
}

Mit

for file in ["1.jpg", "2.png", "3.gif", "4.svg", "5.TIF", "6.webp", "7.HEIC"] {
    if let data = Data(bundleFileName: file) {
        print(file, ImageFormat.get(from: data))
    }
}

///Result
///1.jpg jpg
///2.png png
///3.gif gif
///4.svg unknown
///5.TIF tiff
///6.webp webp
/// 7.HEIC heic

@XueYu, die Antwort hat mir viel geholfen.
Heres ein update für die Daten eher als NSData

struct ImageHeaderData {
    static var PNG: [UInt8] = [0x89]
    static var JPEG: [UInt8] = [0xFF]
    static var GIF: [UInt8] = [0x47]
    static var TIFF_01: [UInt8] = [0x49]
    static var TIFF_02: [UInt8] = [0x4D]
}
enum ImageFormat {
    case Unknown, PNG, JPEG, GIF, TIFF
}
extension Data {
    var imageFormat: ImageFormat {
        var buffer = [UInt8](repeating: 0, count: 1)
        copyBytes(to: &buffer, from: 0..<1)
        if buffer == ImageHeaderData.PNG { return .PNG }
        if buffer == ImageHeaderData.JPEG { return .JPEG }
        if buffer == ImageHeaderData.GIF { return .GIF }
        if buffer == ImageHeaderData.TIFF_01 || 
           buffer == ImageHeaderData.TIFF_02 {
            return .TIFF
        }
        return .Unknown
    }
}