My server doesn't support the HEIF format. So I need to transform it to JPEG before uploading from my app.
I do this:
UIImage *image = [UIImage imageWithData:imageData];
NSData *data=UIImageJPEGRepresentation(image, 1.0);
But how can I know that the data is HEIF (or HEIC) ? I can look at a file:
([filePath hasSuffix:#".HEIC"] || [filePath hasSuffix:#".heic"])
But I don't think it's a good answer. Is there any other solution?
Both existing answers have good recommendations, but to attempt to tell the whole story...
UIImage doesn't represent an image file or even binary data in an image-file format. A UIImage is best thought of as an abstract representation of the displayable image encoded in that data — that is, a UIImage is the result of the decoding process. By the time you have a UIImage object, it doesn't care what file format it came from.
So, as #Ladislav's answer notes, if you have a UIImage already and you just want to get data in a particular image file format, call one of the convenience functions for getting a UIImage into a file-formatted data. As its name might suggest, UIImageJPEGRepresentation returns data appropriate for writing to a JPEG file.
If you already have a UIImage, UIImageJPEGRepresentation is probably your best bet, since you can use it regardless of the original image format.
As #ScottCorscadden implies, if you don't have a UIImage (yet) because you're working at a lower level such that you have access to the original file data, then you'll need to inspect that data to divine its format, or ask whatever source you got the data from for metadata describing its format.
If you want to inspect the data itself, you're best off reading up on the HIEF format standards. See nokiatech, MPEG group, or wikipedia.
There's a lot going on in the HEIF container format and the possible kinds of media that can be stored within, so deciding if you have not just a HEIF file, but an HEIF/HEVC file compatible with this-or-that viewer could be tricky. Since you're talking about excluding things your server doesn't support, it might be easier to code from the perspective of including only the things that your server does support. That is, if you have data with no metadata, look for something like the JPEG magic number 0xffd8ff, and use that to exclude anything that isn't JPEG.
Better, though, might be to look for metadata. If you're picking images from the Photos library with PHImageManager.requestImageData(for:options:resultHandler:), the second parameter to your result handler is the Uniform Type Identifier for the image data: for HEIF and HEIC files, public.heif, public.heif-standard, and public.heic have been spotted in the wild.
(Again, though, if you're looking for "images my sever doesn't support", you're better off checking for the formats your server does support and rejecting anything not on that list, rather than trying to identify all the possible unsupported formats.)
When you are sending to your server you are most likely decoding the UIImage and sending it as Data so just do
let data = UIImageJPEGRepresentation(image, 0.9)
Just decide what quality works best for you, here it is 0.9
A bit late to the party, but other than checking the extension (after the last dot), you can also check for the "magic number" aka file signature. Byte 5 to 8 should give you the constant "ftyp". The following 4 bytes would be the major brand, which I believe is one of "mif1", "heic" and "heix".
For example, the first 12 bytes of a .heic image would be:
00 00 00 18 66 74 79 70 6d 69 66 31
which, after removing 0s and trim the result, literally decoded to ftypmif1.
Well, you could look at magic bytes - JPEG and PNG certainly are known, and I seem to see some references that HEIF (.heic) starts with a NUL byte. If you're using any of the PHImageManager methods like requestImageDataForAsset:options:resultHandler, that resultHandler will be passed a NSString * _Nullable dataUTI reference. There's a decent WWDC video/slides on this (possibly here) that suggest if the UTI is not kUTTypeJPEG you convert it (and the slides have some lower-level sample code in swift to do it that preserve orientation too).
I should also mention, if you have control at your app layer and all uploads come from there, do all this there.
If you're using Photos framework and are importing images from photo library, there's a solution that was mentioned briefly during WWDC17. First, import core services:
import MobileCoreServices
Then, when you request the image, check the UTType that is returned as a second parameter to your block:
// asset: PHAsset
PHImageManager.default().requestImageData(for: asset, options: nil) { imageData, dataUTI, orientation, info in
guard let dataUTI = dataUTI else { return }
if !(UTTypeConformsTo(dataUTI as CFString, kUTTypeJPEG) || UTTypeConformsTo(dataUTI as CFString, kUTTypePNG)) {
// imageData is neither JPG not PNG, possibly subject for transcoding
}
}
Other UTTypes can be found here
I have the following code to turn NSUserDefaults into NSData and then send it with an instance of MFMailComposeViewController:
let defaultsData = NSKeyedArchiver.archivedDataWithRootObject(NSUserDefaults.standardUserDefaults().dictionaryRepresentation())
mailViewController.addAttachmentData(defaultsData, mimeType: "text/txt", fileName: "details.txt")
Pretty simple stuff, but when I send it off I get a .txt that is very garbled where it starts with this:
bplist00‘������òôX$versionX$objectsY$archiverT$top�܆Ø|���ô�ö�õ�ú�ù�û�ü�†�°�¢�£�§�•�¶�ß�®�©�™�´�¨�≠�Æ�Ø�∞�±�≤�≥�¥�µ�∂�∑�∏�π�∫�ª�º�Ω�æ�ø�¿�¡�¬�√�ƒ�≈�∆�«�»�…� �À�Ã�Õ�Œ�œ�–�—�“�”�‘�’�÷�◊�ÿ�Ÿ�⁄�€�‹�›�fi�fl�‡�Ï�Ì�Ó�Ô��Ò�Ú�Û�Ù�˙�˚�¸"#$)*+./367?#ABCDGJVWcfqrstuvwxy|∞±≤≥¥µ∂∑∏π∫ªºΩæø¿¡¬√ƒ≈∆«»… ÀÃÕŒœ–—“”‘’÷◊ÿŸ⁄€‹›fifl‡·Ìıˆ˜˙¡¬√ƒ≈∆«»… ÀÃÕŒœ–—“”‘’÷◊ÿŸ⁄€‹›fifl‡·‚„‰ÂÊÁËÈÍÎÏÌÓÔÒÚÛÙıˆ˜¯˘˙˚¸˝˛ˇ�
!"#$%&'()*+,-./0123456789:;<=>?#ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxy|ÇÉÜáäçéëíóU$null”� �
���R�òWNS.keysZNS.objectsV$classØE�
�������������������
What am I doing wrong?
This is indeed expected. The resulting NSData of NSKeyedArchiver is binary property list (bplist) representation of the dictionary. So you get binary data. What did you expect to receive?
I think I need some assistance in figuring out the correct NSJSONSerialization option to make my problem go away.
On my app I allow the user to select an image from the gallery - the image undergoes the following:
NSData *imageData = UIImageJPEGRepresentation(self.profileImageView.image, 0.0);
then
NSString *stringOfImageData = [imageData base64EncodedStringWithOptions:0];
before it is serialized like this:
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:postDict
options:NSJSONWritingPrettyPrinted
error:&error];
and then sent to my REST API. I then decode it in python using base64 like so:
profileImageData = base64.b64decode(request.json['image'])
It is then loaded in GridFS (mongodb). On extracting the data to send back to the app I first encode in base to base64 before using dumps() to send it back:
dumps(base64.b64encode(fs.get_last_version(request.json['userID']).read()))
Within iOS after receiving the data it goes through the below de-serialization:
[NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers|NSJSONReadingMutableLeaves error:&error]
I have narrowed by problem to the last NSJSONSerialization command. After the data is received by the app it is able to print to screen. After the Serialization I get a 'nil' :(
The Serialization and De-Serialization has been working great for strings, integers etc - it just doesn't work when I'm trying to move image data.
Thanks
EDIT: I am able to run a curl request against the API and then using an online base64 to image converter I can see my image. So it definitely means the issues is with the iOS side of decoding a json encoded base64 string.
EDIT: When I repeatedly run the deserialization - every 20th time or so the data is correctly converted. I think the solution might have to be to break up the data coming in.
EDIT: Error:
parsed error:Error Domain=NSCocoaErrorDomain Code=3840 "The operation couldn’t be completed. (Cocoa error 3840.)" (Unterminated string around character 17.) UserInfo=0x109c08790 {NSDebugDescription=Unterminated string around character 17.}
What you don't say is how you are receiving the data. My guess is you are trying to decode the data before you receive all of it, but since I don't know how it's a guess.
To better understand what's going on, try logging the size and hash of the data, to see if the length varies. You can also save each received data object to the file system - put them in the Documents folder and you can access them from your Mac. If the size never varies you will then have to compare a good data object to a bad one.
In fact you can write a little code to save an image as data and a base64 string, upload it, then pull it back, and save it. Now compare the data and strings. Once you find a difference, then look at. What is its offset from the start? How is it different?
When you understand this all you will be able to fix it.
I 've use
NSData *imageData = [NSData dataWithData:UIImagePNGRepresentation(inImage)];
CC_MD5(imageData, [imageData length], result);
for generate MD5 code of my picture and add them to NSDictionary for compare the image from photoLibrary.
But when I add some code or reboot my device , I find the hash code is totally changed .
How can resolve this problem ?
You should use
NSData *imageData = [NSData dataWithContentsOfFile:file];
CC_MD5(imageData, [imageData length], result);
that must work fine.
Also consider to use sha1 as basing algorithm.
PNG file format allows to have timestamps inside the binary data. This will be different every time you call UIImagePNGRepresentation. I am afraid you can't use MD5 to compare the data of two images this way. Try to extract the raw image data from the files and generate MD5 of the raw data.
As IPA structure is just a zipped file containing compiled codes & media contents like images & audio, how can I protect the contents from being extracted and stolen by others? Is there any encryption I can add into the IPA?
This answer mentions that the application is already encrypted by the time it gets onto your users' devices: Does Apple modify iOS application executables on apps submitted to the App Store?
Sorry, that's only the application binary. The other media are not encrypted, and no, there's no way to encrypt the .ipa. You could try encrypting your images and other media on your system, providing a bunch of application code to decrypt those resources when the app runs, and then your decryption code will become a part of the encrypted application binary. You can't submit an encrypted IPA though, it needs to be the file directly output from Xcode.
In response to your comment, the one I've used in the past is CommonCrypto. You can use this crypto library as a starting point.
Simple usage example of the above:
NSError *error;
NSMutableData *encryptedData = [NSMutableData dataWithContentsOfFile:pathToEncryptedFile];
NSData *decryptedData = [RNDecryptor decryptData:encryptedData
withPassword:#"SuperSecretDecryptionKey"
error:&error];
UIImage *decryptedImage = [UIImage imageWithData:decryptedData];
IMPORTANT NOTE HERE: IF someone was to run the strings utility on your .app on a jailbroken iphone, or even on an iPhone they have filesystem access to via USB, they will get a list of all strings declared in your app. This includes "SuperSecretDecryptionKey". So you may want to use an integer, floating-point or other constant to do on-the-fly generation of a string decryption key, or make sure that the string you use to decrypt things is exactly the same as a normal system string so no-one suspects it as the true key. Security through obscurity, in this case, is advantageous.
To encrypt/decrypt *.strings files, you should encrypt the key and value strings in some manner (maybe one which gives you hexadecimal back, or any alphanumeric characters), and when you want to access a given value, say LicenceNumber, do this:
NSError *error;
NSData *unencryptedKey = [#"LicenceNumber"
dataUsingEncoding:NSUTF8StringEncoding];
NSData *encryptedKey = [RNEncryptor encryptData:unencryptedKey
withSettings:kRNCryptorAES256Settings
password:#"SuperSecretEncryptionKey"
error:&error]
NSData *encryptedValue = [[NSBundle mainBundle]
localizedStringForKey:[NSString
stringWithUTF8String:[encryptedKey bytes]]
value:#"No licence"
table:#"EncryptedStringsFile"];
NSData *decryptedValue = [RNDecryptor decryptData:encryptedValue
withPassword:#"SuperSecretDecryptionKey"
error:&error];