ios - UIImage 作为表示但没有文件扩展名

Question

我想将图像转换为

UIImagePNGRepresentation
UIImageJPEGRepresentation

但是我不知道文件类型。我刚得到一个没有扩展名的 URL。有没有办法将图像从 URL 保存到文件系统？

// got the data from the URL

let imageData = UIImage(data: data!)

// now I want to write to the filesystem but only way was with a representation as UIImage has no write

if let saveImageData = UIImageXXXXXXRepresentation(imageData!) {
try saveImageData.write(to: URL(fileURLWithPath: localFilename), options: [.atomic])
}

Answer 1

从 URL 中获取图像数据，然后从该数据对象中检查图像类型，如下所示

swift 3

let data: Data = UIImagePNGRepresentation(yourImage)!

extension Data {
    var format: String {
        let array = [UInt8](self)
        let ext: String
        switch (array[0]) {
        case 0xFF:
            ext = "jpg"
        case 0x89:
            ext = "png"
        case 0x47:
            ext = "gif"
        case 0x49, 0x4D :
            ext = "tiff"
        default:
            ext = "unknown"
        }
        return ext
    }
}

objective-c

+ (NSString *)contentTypeForImageData:(NSData *)data {
    uint8_t c;
    [data getBytes:&c length:1];

    switch (c) {
    case 0xFF:
        return @"image/jpeg";
    case 0x89:
        return @"image/png";
    case 0x47:
        return @"image/gif";
    case 0x49:
    case 0x4D:
        return @"image/tiff";
    }
    return nil;
}

检查完上面你可以存储带有所选扩展名的图像

要从数据中获取扩展，您可以从 here 查看还有