As the title says,i am using GZip to compress and decompress the string.But in between that i want to read the compressed string,how do i read that unknown compressed string?.
What i tried so far:
Using GZip(from github),i tried compressing the string as below...
//UML string
NSString *plantUmlString = #"#startuml\n Bob -> Alice : hello \n#enduml"
String compression...
NSData *originalData = [plantUmlString dataUsingEncoding:NSASCIIStringEncoding];
NSString *compressedString = [[originalData gzippedData] base64EncodedStringWithOptions:kNilOptions];
NSLog(#"%#", compressedString);//H4sIAAAAAAAAA8tIzcnJV0gvrSwuKcrMSw8tBhKuecn5KQCRj54cGQAAAA
Where i am struggling:
compressedString is returning "H4sIAAAAAAAAA8tIzcnJV0gvrSwuKcrMSw8tBhKuecn5KQCRj54cGQAAAA"
instead of "SzIrIxBAICt9oGS0",this is the actual string i should get.If i decode the generated compressedString,i am getting nill...And if i use UTF-8 encoding i am getting "null"..How do i read the actuall string here?
NOTE: if i decompress the above compressed data,i am getting original string before compressing...
NSData *decodedData = [[NSData alloc] initWithBase64EncodedString:compressedString options:0];
NSString *decompressedString=[[NSString alloc] initWithData:[decodedData gunzippedData] encoding:NSASCIIStringEncoding];
NSLog(#"%#",decompressedString);
//Correct: decompressedString returning me the original string before compressing...
What i am trying to do:
Trying to generate a flowchart using the PlantUML Server,which accepts the compressed UML string and returns me the flowchart image...
Some more information : If i compress the above UML string in android(which is available in github) i am getting "SzIrIxBAICt9oGS0" as the string...But in Objective-C i am reading entirely different string...
Am i doing something worng with the encoding?...Any advice/solution is really helpful...
According to the sample code at http://plantuml.sourceforge.net/codephp.html , it uses compression level 9, so you probably want to use that, if you want to exactly match that string.
Related
I had my server encoding in ISO-8859-1 and decided to chango into UTF-8. The problem is that the filenames creates in ISO now crashes because I change the encoding type in my code. I try to connect with an iOS app and show the directories and files, the news are shown well but the olds with ISO not.
How can I detect if the filename is in one or other encoding to process in the right way each one? Because now, the filename in ISO it can be represent in UTF-8 but the string to access is not the same. (Ex: %E1p%F1 --> %C3%A1p%C3%B1)
I try this, but it doesn't work:
NSString *isoL = [item.href stringByAddingPercentEscapesUsingEncoding:NSISOLatin1StringEncoding];
char const *iso2utf = [isoL UTF8String];
NSString *utf = [[NSString alloc]initWithCString:iso2utf encoding:NSUTF8StringEncoding];
You need to have the server declare the content encoding of the response, much like how HTTP does.
I don't believe it's possible to auto-detect ISO-8859-1/UTF-8 text encoding.
I have A NSdata value that it needs to be converted into a string.
So far my app works fine loading a QC composition from a server however, I have a warning when I tell QC to load data from server.
It loads the file just fine but is there a way to avoid this worming?
I have tried to convert data to string using
NSString* newStr = [[NSString alloc] initWithData:urlData
encoding:NSUTF8StringEncoding];
HOwever, it is giving a null location of the file
Find the way I was loading the file with wrong method the correct one is:
QCComposition *qc = [QCComposition compositionWithData:urlData];
Let me start off by saying that I am not particularly trying to find a solution, just the root cause of the problem. I am trying to retrieve a JSON from a url. In browser, the url call works just fine and I am able to see the entire JSON without issue. However, in x-code when simply using NSURLConnection, I am getting data bytes, but my NSString is null.
theString = [[NSString alloc] initWithData:urlData encoding:NSUTF8StringEncoding];
After doing some research I have found that I am probably trying to use the wrong encoding. I am not sure what type of encoding is being used by the url, so on first instinct I just tried some random encoding types.
NSString* myString = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
NSString* myString2 = [[NSString alloc] initWithData:data encoding:NSUTF16StringEncoding];
NSString* myString3 = [[NSString alloc] initWithData:data encoding:NSWindowsCP1252StringEncoding];
NSASCIIStringEncoding and NSWindowsCP1252StringEncoding is able to bring back a partially correct JSON. It is not the entire JSON thatI am able to view in the browser, and some characters are a little messed up, but it is something. To try and better determine what encoding was used, I decided to use the following method to try and determine it by looking at what encoding returned.
NSError *error = nil;
NSStringEncoding encoding;
NSString *my_string = [[NSString alloc] initWithContentsOfURL:url
usedEncoding:&encoding
error:&error];
My NSStringEncoding value is 3221214344. And this number is consistent everytime I run the app. I can not find any NSStringEncoding values that even come close to matching this.
My final question is: Is the encoding used for this url not consumable by iOS, is it possible that multiple types of encoding was used for this url, or is there something else that I could be doing wrong on my end?
It's best not to rely on Cocoa to figure out the string encoding if possible, especially if the data might be corrupted. A better approach would be to check if the value indicated by the HTTP Content-Type header specifies a character set like in this example:
Content-Type: text/html; charset=ISO-8859-4
Once you're able to parse and retrieve a character set name from the Content-Type header, you need to convert it to an NSStringEncoding, first by passing it to CFStringConvertIANACharSetNameToEncoding, and then passing the returned CF string encoding to CFStringConvertEncodingToNSStringEncoding. After that, you can initialize your string using -[NSString initWithData:encoding:].
NSData *HTTPResponseBody = …; // Get the HTTP response body
NSString *charSetName = …; // Get a charset name from the Content-Type HTTP header
// Get the Core Foundation string encoding
CFStringEncoding cfencoding = CFStringConvertIANACharSetNameToEncoding((CFStringRef)charSetName);
// Confirm this is a known encoding
if (cfencoding != kCFStringEncodingInvalidId) {
// Initialize the string
NSStringEncoding nsencoding = CFStringConvertEncodingToNSStringEncoding(cfencoding);
NSString *JSON = [[NSString alloc] initWithData: HTTPResponseBody
encoding: nsencoding];
}
You still may run into problems if the string data you're working with is corrupted. For example, in the above code snippet, perhaps charSetName is UTF-8, but HTTPResponseBody can't be parsed as UTF-8 because there's an invalid byte sequence. In this situation, Cocoa will return nil when you try to instantiate your string, and short of sanitizing the data so that it conforms to the reported string encoding (perhaps by stripping out invalid byte sequences), you may want to report an error back to the end user.
As a last-ditch effort — rather than reporting an error — you could initialize a string using an encoding that can handle anything you throw at it, such as NSMacOSRomanStringEncoding. The one caveat here is that unicode / corrupted data may show up intermittently as symbols or unexpected alphanumerics.
Even though it seems that the answer has been provided in the comments (using iso-8859-1 as the correct encoding) I thought it worthwhile to discuss how I would go about debugging this problem.
You said that the Desktop Browser (Chrome) can digest the data correctly, so let's use that:
Enable Developer Tools https://developers.google.com/chrome-developer-tools/
When the Dev Tools window is open, switch to "network" and execute your call in that browser tab
check the output by clicking on the request url - it should give you some clue.
If that doesn't work, tools like Postman can help you to recreate the call before you implement it on the device
I'm trying to parse and English Dictionary from an RTF file into an array.
I originally had it working, but I'm not sure why it isn't now.
In the dictionary, each word is separated by a new line (\n). My code so far is:
//loading the dictionary into the file and pull the content from the file into memory
NSData *data = [NSData dataWithContentsOfFile:#"wordList.rtf"];
//convert the bytes from the file into a string
NSString *string = [[NSString alloc] initWithBytes:[data bytes]
length:[data length]
encoding:NSUTF8StringEncoding];
//split the string around newline characters to create an array
NSArray *englishDictionary = [string componentsSeparatedByString:#"\n"];
When I try and NSLog it, it just comes up with (null)...
I've already looked at: Objective-C: Reading a file line by line
But couldn't get the answer by Yoon Lee working properly. It prints out with two back slashes at the end as well as lots of unnecessary stuff at the start!
Any help would be greatly appreciated! Cheers!
Try using a plain text (txt) file instead of rtf. RTF files contain formatting information about the text as well. Thats the unnecessary stuff that you see after reading the content.
What is the easiest and fastest code to do a conversion between NSData and a base64 string? I've read a bunch of solutions at SO and mostly they involve in adding another class etc. I found a great solution here but it's too complex.
Scroll down to the Conclusion section on the page you linked and download the provided NSData+Base64 files. Its the best solution I have seen so far and is incredibly easy to use. If you can learn anything about Cocoa, you can learn to use that project.
Example
NSString *originalString = [NSString stringWithFormat:#"test"];
NSData *data = [NSData dataFromBase64String:originalString];
NSLog([data base64EncodedString]);
The above will print out the original string after converting it to base64 and back to a normal unencoded string.
As of iOS 7, NSData now directly provides this functionality with the new methods -base64EncodedDataWithOptions: and -base64EncodedStringWithOptions:. (The options let you specify that the string is/should be line-wrapped, the better to deal with email, and user-facing displays.)
You don't need any custom implementation. Creating base64 from NSData is shown in other answers. There is opposite direction. From Base64 string to NSData:
NSString *base64Encoded = #"some base64 string";
NSData *nsdataFromBase64String = [[NSData alloc] initWithBase64EncodedString:base64Encoded options:0];
I ended up using this same class as provided by SUDZC
implementation was easy first I did an import
#import "NSData+Base64.h"
then I was able to call my data.
NSData *data = [[NSData alloc] initWithData:[NSData dataWithBase64EncodedString:strData]];
Be aware that there are more Base64 formats.
For example JWTs use a URL safe format.
Or you may take a look to the (quite new) CryptoCompatibility sample project, I think there is a wrapper class for base64 operation. It is a MacOS sample but it uses the library libresolve.dylib with I think is available on iOS too (is see it at least here in iOS7).