I have an array that I serialize, encrypt and then write into a file. The data itself appears to be good but I'm having problems restoring the array back from the file. Here is what I do
NSString *filename = [[self getTransactionLogPath] stringByAppendingPathComponent:transactionLogName];
NSData *data = [[NSData alloc] initWithContentsOfFile:filename];
NSLog(#"encrypted data: %#", data);
EncryptedData *decoder = [[EncryptedData alloc] init];
NSData *decrypted = [decoder reverseTransformedValue:data];
NSArray *array = [NSKeyedUnarchiver unarchiveObjectWithData:decrypted];
I get the filename and read the data from file. EncryptedData decoder runs AES128 on the data and finally I unarchive the array.
The problem is that unarchiveObjectWithData throws an exception
[NSKeyedUnarchiver initForReadingWithData:]:
incomprehensible archive
The tricky thing is that the code works fine in simulator if I keep the NSLog line i.e. I print out the data after reading the file.
On device the NSLog() does not help. Is this a threading problem where the unarchiver starts before the data is read?
I tried adding a delay instead of the NSLog() line but that didn't help.
Any other ways to do the job if I want to encrypt the array before writing to file?
I have recently started Application development on MAC OS 10.6, I am trying to modify a "key/value" pair in a local JSON file on my MAC machine using SBJSON. I have successfully read the value of a key, but I am not able to get that how to modify the value of a key and synchronize this to the JSON file. Lets suppose, I have a following JSON Data int o a local file:
{
"name": {
"fName":"John",
"lName":"Doe"
}
}
And i want to change the value of "fName" to something else, like Robert.
I have tried alot searching about it, but got no clue... Can anyone help me.
I am using SBJSON Framework!
Code:
NSString *filePath = #"/Users/dev/Desktop/SQLiteFile/myJSON2.json";
NSData *myData = [NSData dataWithContentsOfFile:filePath];
NSString *responseString = [[NSString alloc] initWithData:myData encoding:NSUTF8StringEncoding];
NSLog(#"FILE CONTENT : %#", responseString);
SBJsonParser *jsonParser = [[SBJsonParser alloc] init];
NSDictionary * dictionary = (NSDictionary*)[jsonParser objectWithString:responseString error:NULL];
[dictionary setObject:#"Robert" forKey:#"fName"];
//
// Code for writing this change into the file, which i needed.
//
[jsonParser release];
You want a mutable deep copy of your dictionary. Then you'll be able to modify it.
I am allowing for application data (it's a Mac app on 10.7) to be exported as an XML file, and one field I would like to be able to export/import to/from XML is an NSData field. What would be the correct/accepted way of doing this? Should I convert to base64 and write that string to XML?
I would prefer not to roll my own solution, using a category, as the accepted answer to the linked question does (linking to Matt Gallagher's solution).
Update
I just discovered the NSPropertyListSerialization class. I got my hopes up, but it only has static serialization methods which return NSData representations.
I realized (as my updated alluded to) that I could use the NSPropertyListSerialization class, since the NSData returned by -dataWithPropertyList:format:options:error: is just a UTF-8 string. This is what I'm using to serialize:
NSData *data = value;
NSError *error = nil;
NSData *plistData = [NSPropertyListSerialization dataWithPropertyList:data
format:NSPropertyListXMLFormat_v1_0
options:0
error:&error];
if (error) {
NSLog(#"Error serializing data to plist XML: %#", error);
} else {
NSString *plistString = [[NSString alloc] initWithData:plistData encoding:NSUTF8StringEncoding];
NSXMLElement *dataElement = [NSXMLElement elementWithName:field
stringValue:plistString];
}
And deserialize:
NSData *plistData = [element.stringValue dataUsingEncoding:NSUTF8StringEncoding];
NSData *originalData = [NSPropertyListSerialization propertyListWithData:plistData
options:NSPropertyListImmutable
format:NULL
error:&error];
if (error) {
NSLog(#"Error deserializing data from plist XML: %#", error);
} else {
value = originalData;
}
I am using google contact data objective c APIs for fetching contacts. I got contacts array from google server now i want to write contact to file. i am using writeToFile:atomically: method for writing array to file but This method is not working for me since i feel that output array from gdata API not contain property list objects. Please suggest any alternate solution.
-(void)fetchData{
GDataServiceGoogleContact *service=[[GDataServiceGoogleContact alloc] init];
[service setShouldCacheResponseData:YES];
[service setServiceShouldFollowNextLinks:YES];
[service setUserCredentialsWithUsername:[mUsername stringValue] password:[mPassword stringValue]];
// GENERATING THE URL
NSURL *feedURL=[GDataServiceGoogleContact contactFeedURLForUserID:kGDataServiceDefaultUser];
GDataQuery *contQuery=[GDataQueryContact contactQueryWithFeedURL:feedURL];
[contQuery setShouldShowDeleted:YES];
[contQuery setMaxResults:2000];
GDataServiceTicket *ticket=[service fetchFeedWithQuery:contQuery delegate:self didFinishSelector:#selector(hasFetchedContacts:feed:error:)];
}
-(void) hasFetchedContacts:(GDataServiceTicket*) ticket feed:(GDataFeedContact*) contacts error:(NSError*) err
{
NSArray *contactList=[contacts entries];
NSLog(#"%d",[list writeToFile:#"/Users/subhranil/Desktop/contactList" atomically:NO]);
}
Wrap it up to NSData with:
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:contactList];
Then save NSData to file with:
[data writeToFile:#"/Users/subhranil/Desktop/contactList" atomically:NO];
You can later restore the data back to NSArray using:
NSData *data = [NSData dataWithContentsOfFile: #"yourFilePath"];
NSArray *array = [NSKeyedUnarchiver unarchiveObjectWithData:data]
Just make sure that objects inside your NSArray conform to NSCoding.
You can use byte array for this purpose and NSData for writing to file.
For saving:
NSData *data=[[NSData alloc] initWithBytes:[contacts entries] length:total];
[data writeToFile:#"path" atomically:YES];
total= The total size of the array in bytes
For retrieving:
NSData *newdata = [NSData dataWithContentsOfFile:#"path"];
NSUInteger len = [newdata length];
Byte *byteData = (Byte*)malloc(len);
memcpy(byteData, [newdata bytes], len);
byteData will now contain an array of GDataEntryContact objects and you can use them accordingly.
You can encode/decode GDataObject using an xml as generator.
Encode:
[entry setNamespaces:[entry completeNamespaces]];
NSString *xml = [[entry XMLElement] XMLString];
if (nil != xml)
{
//Store your xml NSString to a file
}
Decode:
NSString *xml = //Read your XML String from file;
NSXMLElement *xmlElement = [[NSXMLElement alloc] initWithXMLString:xml error: &error];
if (!error) {
return [[GDataEntryDocBase alloc] initWithXMLElement:xmlElement parent: nil];
}
I'm trying to combine images in my app into one file and write it to disk.
NSMutableArray *array = [NSMutableArray arrayWithObjects:
[NSData dataWithContentsOfFile:#"0.png"],
[NSData dataWithContentsOfFile:#"1.png"],
[NSData dataWithContentsOfFile:#"2.png"],
nil];
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:array];
NSError *error = nil;
NSString *path=#"/Users/myusername/Desktop/_stuff.dat";
[data writeToFile:path options:NSDataWritingAtomic error:&error];
or
NSArray *array = [NSArray arrayWithObjects:
[NSImage imageNamed:#"0"],
[NSImage imageNamed:#"1"],
[NSImage imageNamed:#"2"],
nil];
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:array];
NSError *error = nil;
NSString *path=#"/Users/myusername/Desktop/_stuff.dat";
[data writeToFile:path options:NSDataWritingAtomic error:&error];
But both produce a file that is 4KB (empty). If I NSLog the error it is (null). Am I making the data the wrong way?
Edit: If I open the resulting file with a text editor, it looks like this:
I wrote a quick example:
Missing: memory management / error handling / proper file handling
// Archive
NSMutableArray *array = [[NSMutableArray alloc] init];
NSString * input = #"/Users/Anne/Desktop/1.png";
[array addObject:[NSData dataWithContentsOfFile:input]];
[array addObject:[NSData dataWithContentsOfFile:input]];
[array addObject:[NSData dataWithContentsOfFile:input]];
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:array];
NSString *path = #"/Users/Anne/Desktop/archive.dat";
[data writeToFile:path options:NSDataWritingAtomic error:nil];
// Unarchive
NSMutableArray *archive = [NSKeyedUnarchiver unarchiveObjectWithFile:path];
NSData * firstObject = [archive objectAtIndex:0];
NSString * output = #"/Users/Anne/Desktop/2.png";
NSURL *fileURL = [[NSURL alloc] initFileURLWithPath:output];
[firstObject writeToURL:fileURL atomically:YES];
You can also add NSImages to the NSMutableArray:
NSString * input = #"/Users/Anne/Desktop/1.png";
NSImage *image = [[NSImage alloc] initWithContentsOfFile: input];
[array addObject:image];
But that will significantly increase the file size.
Response to the following comment:
So if I only need to access an image at runtime (in the archive), is there a way to access that image at an index without unarchiving the whole thing? Seems like unnecessary overhead to me.
I assume you're still struggling with this problem?
Hiding (or encrypting) app resources?
Like i mentioned earlier, combining all files into one big file does the trick.
Just make sure you remember the file-length of each file and file-order.
Then you can extract any specific file you like without reading the whole file.
This might be a more sufficient way if you only need to extract one file at the time.
Quick 'dirty' sample:
// Two sample files
NSData *fileOne = [NSData dataWithContentsOfFile:#"/Users/Anne/Desktop/1.png"];
NSData *fileTwo = [NSData dataWithContentsOfFile:#"/Users/Anne/Desktop/2.png"];
// Get file length
int fileOneLength = [fileOne length];
int fileTwoLength = [fileTwo length];
// Combine files into one container
NSMutableData * container = [[NSMutableData alloc] init];
[container appendData:fileOne];
[container appendData:fileTwo];
// Write container to disk
[container writeToFile:#"/Users/Anne/Desktop/container.data" atomically:YES];
// Read data and extract sample files again
NSData *containerFile = [NSData dataWithContentsOfFile:#"/Users/Anne/Desktop/container.data"];
NSData *containerFileOne =[containerFile subdataWithRange:NSMakeRange(0, fileOneLength)];
NSData *containerFileTwo =[containerFile subdataWithRange:NSMakeRange(fileOneLength, fileTwoLength)];
// Write extracted files to disk (will be exactly the same)
[containerFileOne writeToFile:#"/Users/Anne/Desktop/1_extracted.png" atomically:YES];
[containerFileTwo writeToFile:#"/Users/Anne/Desktop/2_extracted.png" atomically:YES];
// Only extract one file from the container
NSString * containerPath = #"/Users/Anne/Desktop/container.data";
NSData * oneFileOnly = [[NSFileHandle fileHandleForReadingAtPath:containerPath] readDataOfLength:fileOneLength];
// Write result to disk
[oneFileOnly writeToFile:#"/Users/Anne/Desktop/1_one_file.png" atomically:YES];
Tip:
You can also save the 'index' inside the container file.
For example: The first 500 bytes contain the required information.
When you need a specific file: Read the index, get the file position and extract it.
You are archiving a NSMutable array of NSImage. This two classes conform to the NSCoding protocol required by NSKeyedArchiver, so I don't see where would be your problem.
So, here are many ideas to test.
First, are you sure that the data you think you have are valid? In your first code snippet, you write [NSData dataWithContentsOfFile:#"0.png"]. This method expects an absolute file path.
Assuming the problem is not in your code, just in your question, let's continue:
Do you have something different than nil in the variable data after your archiving? Ie, after the assignement to data, can you add this code. If the assertion fail, you will get an exception at runtime:
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:array];
NSAssert(nil != data, #"My object data is nil after archiving");
If the problem was not here, what is the return of the line [data writeToFile:path options:NSDataWritingAtomic error:&error];
(Not the variable error, but the return value of the call to the method - writeToFile: options: error:)
What happens if you simplify your code and just do this:
result = [NSKeyedArchiver archiveRootObject:data
toFile:archivePath];
If everything was ok, have you tried to unarchive your file with NSKeyedUnarchiver?
The problem is that [NSData dataWithContentsOfFile:#"0.png"] looks for the file "0.png" in the current directory, but what the application thinks of as the current directory is probably not the place you're expecting. For graphical apps, you should always either use an absolute path or a path relative to some place that you can get the absolute path of (e.g. your app bundle, the application support directory, some user-selected location).
For command-line tools, using the current directory is more common. But I doubt that's the case here.
Another thing I noticed on Mavericks and up is that the folders in the path must be in existence. Meaning you must create the folder structure prior to saving into that folder. If you try to write to a folder on the desktop or elsewhere, even with sandboxing off, it will fail if the folder does not exist. I know this has been answered already, but I found that my issue continued regardless, but once I make sure that the folder structure was in place, I could do my writing to that folder.
On a side note: I'm sure that you could do this from NSFileManager, and I'll be doing that myself once I finalize my app structure, but hope this helps someone else lost in the sauce.