Swift开发根据图片的data获取图片的格式

可以根据自己的需求返回相应的结果
extension Data{
    func getImageFormat()->(String?){
        var c:UInt8 = UInt8()
        self.copyBytes(to: &c, count: 1)
        switch c {
        case 0xFF:
            return "image/jpeg"
        //  return ".jpg"
        case 0x89:
            return "image/png"
        //  return ".png"
        case 0x47:
            return "image/gif"
        //  return ".gif"
        case 0x4D:
            return "image/tiff"
        //  return ".tiff"
        default:
            return "image/jpeg"
        //  return ".png"
        }
    }
}

参考资料：http://www.cocoachina.com/bbs/read.php?tid-243736.html