Question

我想将图片转换为

UIImagePNGRepresentation
UIImageJPEGRepresentation

但是我不知道文件类型。我刚刚获得了一个没有扩展名的网址。有没有将图像从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获取imageData，然后从该数据对象中检查下面的图像类型

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
    }
}

目标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;
}

上面检查后，您可以存储具有所选扩展名的图像

要从数据中获取扩展程序，您可以从here检查

Answer 2

使用该方法通过使用图像的NSData检查图像的扩展名。

func contentTypeForImageData(data: NSData) -> String {
    var c: UInt8
    data.getBytes(c, length: 1)
    switch c {
        case 0xFF:
            return "image/jpeg"
        case 0x89:
            return "image/png"
        case 0x47:
            return "image/gif"
        case 0x49, 0x4D:
            return "image/tiff"
    }

    return nil
}

UIImage作为表示但没有文件扩展名

2 个答案: