I have some image data (jpeg) I want to send from my iPhone app to my webservice. In order to do this, I'm using the NSData from the image and converting it into a string which will be placed in my JSON.
Currently, I'm doing this:
NSString *secondString = [[NSString alloc] initWithBytes:[result bytes]
length:[result length]
encoding:NSUTF8StringEncoding];
Where result is of type NSData. However, secondString appears to be null even though result length returns a real value (like 14189). I used this method since result is raw data and not null-terminated.
Am I doing something wrong? I've used this code in other areas and it seems to work fine (but those areas I'm currently using it involve text not image data).
TIA.
For binary data, better to encode it using Base64 encoding then decode it in you webservice. I use NSData+Base64 class downloaded from here, this reference was also taken from Stackoverflow, an answer made by #Ken (Thanks Ken!).
You are not converting the data to a string. You are attempting to interpret it as a UTF-8 encoded string, which will fail unless the data really is a UTF-8 encoded string. Your best bet is to encode it somehow, perhaps with Base64 as Manny suggests, and then decode it again on the server.
Related
I'm working on an iOS app using Parse, and I need to simulate their encryption flow using Ruby for the website and browser extensions I'm building for it.
For generating the salt for AES, they have the following code in the iOS app:
NSString *str = user.email;
NSData *strData = [str dataUsingEncoding: NSUTF8StringEncoding];
NSData *encryptedData = [strData AESEncryptWithPassphrase:str]; // using the same key
What's puzzling me is dataUsingEncoding: NSUTF8StringEncoding -- it's obviously encoding the string in UTF-8, but when I see it in NSLog it seems quite different. So if str was "randomemail#gmail.com", doing NSLog on strData outputs:
<72616e64 6f6d656d 61696c40 676d6169 6c2e636f 6d>
Now, how do I get that same output in Ruby? I can't get the right salt because of this ("randomemail#gmail.com".encode("UTF-8") simply returns the email as expected). How can I simulate dataUsingEncoding in Ruby to get the same exact salt, is there something I'm missing?
Thanks
Try this:
"randomemail#gmail.com".encode("UTF-8").bytes.to_a.map{ |x| x.to_s(16)}
and you will "see" what you want.
The hexadecimal representation of "randomemail#gmail.com" with UTF-8 encoding is
<72616e64 6f6d656d 61696c40 676d6169 6c2e636f 6d>
But ruby shows you the string representation, which is "randomemail#gmail.com".
They are showing the same stuff in different ways.
Check here for more information.
I'm allowing the users of my app to either take a pic or select one from their library. When selected I need to get the images' data and convert it to a string so I can send it to a web service.
The problem I'm currently having is that [NSString initWithData:] is returning nil when I have the encoding set to UTF8. I need to set it to UTF8 for the XML message.
NSString *dataString = [[NSString alloc] initWithData:UIImageJPEGRepresentation(theImage, 1.0) encoding:NSUTF8StringEncoding];
Thanks for any advice!
You can't convert an UIImage to NSString by using initWithData:encoding: method. This method is only for converting an string's data to NSString (an Text File for example).
If you are trying to convert any kind of binary data to NSString, there are some kind of encoding available. Base64 is widely used. Also your server should have the ability to decode what you've sent.
In addition, in most cases, send an image to server just need to POST it in binary as it used to be.
I am converting image to NSdata using UIImageJPEGRepresentation(image, 1.0) and then encoding it to base64 using base64 helper class
NSString *imageOne = [self encodeBase64WithData:[imageDict objectForKey:#"ImageOne"]];
and finally sending it to server using post method as json parameter and in server side using php method to decode it.
/* encode & write data (binary) */
$ifp = fopen($imageNameWithPath, "wb" );
fwrite($ifp, base64_decode($base64ImageString));
fclose($ifp);
After decoding it, I am saving the file as jpeg image and the file is created with proper size and extension but problem is that when I open it, I get the DIMENSION OF IMAGE as 0X0 ..(problem is here)
Server side script is correct as our android developer is also sending base64string and the image is saved as jpeg with proper size and dimension.
This problem is only from iphone side when sending to server for decoding. I have decoded the image using my base64 helper class and it works fine on my iPhone device.
UIImageView *viewImage = [[UIImageView alloc] initWithImage:[UIImage imageWithData: [self decodeBase64WithString:[registerDataDict objectForKey:#"imageOne"]]]];
[self.view addSubview:viewImage];
Is the process followed by me correct on the device or do I need to change something? Help would be appreciated.
There are variants on the extra chars used to get to the 65 needed for base64 encoding (26 uppercase + 26 lowercase + 10 digits = 62), and different encoders may use a different subset. PHP is expecting them to be ['+', '/', '='], your application may be using something like ['-', '_', '='].
Once you figure out what the mapping is you can use str_replace before the decode in php.
See the wikipedia page on base64 or the php documentation for base64_decode for more info.
I'm successfully using this with several OAuth providers: Base64Transcoder.c It's a C class, you can easily turn it into a Objective-C class if you like.
I'm encoding like this:
char base64Result[32];
size_t theResultLength = 32;
[Base64Transcoder base64EncodeData:digest digestLength:CC_SHA1_DIGEST_LENGTH base64Result:base64Result resultLength:&theResultLength];
NSData *theData = [NSData dataWithBytes:base64Result length:theResultLength];
NSString *base64EncodedResult = [[NSString alloc] initWithData:theData encoding:NSUTF8StringEncoding];
Hmm well, I turned the C function base64EncodeData of the original class into an Objective-C method but you get the idea.
The parsing of a file containing XML breaks when ever there is a string containing '?'. As an example you can see the line below.
<Radio id="32">
<stationName>BBC 5 Live</stationName>
<streamType>aac+</streamType>
<streamBandwidth>48kbps</streamBandwidth>
<streamURL>http://bbcmedia.ic.llnwd.net/stream/bbcmedia_he2_5live_q?s=1308038932&e=1308053332&h=868e4fa343b375695183f6a3bd0267d9</streamURL>
</Radio>
Is there some way to encode the '?' or what is the way thats generally used to handle this kind of problem, as I would imagine this would be encountered a lot.
The line of code that handles this (i believe) is :
[aRadio setValue:currentElementValue forKey:elementName];
Though I maybe that is not where it breaks.
Many Thanks,
-Code
Most probably, the problem is not the '?' character, but the '&' characters in your URL. The '&' character has a special meaning in XML (it is used to start entities like & or <), so the XML parser will fail if it doesn't find a valid entity. The way to go is to wrap the value in a CDATA section as deanWombourne suggests.
Try this. Convert it into UTF8
NSData *data = [myString dataUsingEncoding:NSUTF8StringEncoding];
Then parse with this data...
NSXMLParser *parser = [[NSXMLParser alloc] initWithData:data];
There's a few ways of dealing with this.
1) Percent encode the string before sending from the server (your '?' would become '%3F') and decode the data when you receive in in your app. - see this answer for more details.
2) Use CDATA markers around this bit of data - see here for more details
I am aware this question has been asked several times, but I was unable to find a definate answer that would best fit my situation.
I want the ability to have the user select an image from the library, and then that image is converted to an NSData type. I then have a requirement to call a .NET C# webservice via a HTTP get so ideally I need the resulting string to be UTF8 encoded.
This is what I have so far:
NSData *dataObj = UIImageJPEGRepresentation(selectedImage, 1.0);
[picker dismissModalViewControllerAnimated:YES];
NSString *content = [[NSString alloc] initWithData:dataObj encoding:NSUTF8StringEncoding];
NSLog(#"%#", content);
The NSLog statement simply produces output as:
2009-11-29 14:13:33.937 TestUpload2[5735:207] (null)
Obviously this isnt what I hoped to achieve, so any help would be great.
Kind Regards
You can't create a UTF-8 encoded string out of just any arbitrary binary data - the data needs to actually be UTF-8 encoded, and the data for your JPEG image obviously is not. Your binary data doesn't represent a string, so you can't directly create a string from it - -[NSString initWithData:encoding:] fails appropriately in your case.
Assuming you're using NSURLConnection (although a similar statement should be true for other methods), you'll construct your NSMutableURLRequest and use -setHTTPBody: which you need to pass an NSData object to. I don't understand why you would be using a GET method here since it sounds like you're going to be uploading this image data to your web service - you should be using POST.