NSLog displays unknown garble with the following code:
NSString *sampleStr = #"你好";
NSLog(sampleStr);
But it outputs:
As I send the above characters to backend, backend shows
?????
How do I fix this problem?
What the problem specifically? NSLogging or the backend one?
If the former, first of all, you should use string formatting to output strings instead of passing the NSString object directly. This must give you desired output:
NSLog(#"%#", sampleStr);
Though, I tried your code without changes in Xcode 13.1 and it gave me the desired output nevertheless. So, probably the problem is somewhere else, not in your NSLog:
NSString *sampleStr = #"你好";
// "Format string is not a string literal (potentially insecure)"
NSLog(sampleStr); // 你好
NSLog(#"%#", sampleStr); // 你好
If you mean backend as your problem, it depends on how you "send" it to backend (in a body as data, as an HTTP parameter as text, with/without escaping, etc.) and whether your backend code supports the input you provide. To answer that more precisely we should have more information.
Related
First off, I'm not exactly sure what is happening or if I fully understand it enough to describe the issue so I'll try my best.
I'm encoding a NSData object that contains json and one of the objects contains a degree symbol. We believe this what is causing the issue and would like to remove it before encoding since the problem occurs during encoding.
I have plenty of options out there for removing certain characters from strings but none from doing it from the NSData object itself. Wondering if this is even possible or if its an issue with how I'm already encoding it.
This is how the NSData object is being encoded and turned back into a NSData object to serialize it to json. Right now I'm not trying to remove the degree symbol, using Latin 1 because another character I want to use but do not need it, this probably isn't the best way to do but it works for majority of other data objects that pass through it just not this one so this needs to change.
NSString* stringISOLatin1 = [NSString stringWithCString:data.bytes encoding:NSISOLatin1StringEncoding];
NSData* dataUTF8 = [stringISOLatin1 dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:NO];
The results are a little weird, most of the time it works fine, even including the degree symbol in the text when displayed on screen. Other times after encoding the string comes back messed up at the end which makes it unable to be serialized.
Any help would be appreciated even if it just leads to a better explanation of what is happen. Thanks
The problem is likely that you are using NSString:stringWithCString:encoding: to convert your data object. This function requires the data to be null terminated. NSData objects do not have to be NULL terminated because they have an explicit length. If the NULL character is missing it will continue to read whatever there happens to be after the string, giving you either garbage at the end or possibly crash because of memory violation.
Instead try using this:
NSString *stringISOLatin1 = [[NSString alloc] initWithData:data encoding:NSISOLatin1StringEncoding];
I'm writing RSS reader and taking article urls from feeds, but often have invalid urls while parsing with NSXMLParser. Sometimes have extra symbols at the end of url(for example \n,\t). This issue I fixed.
Most difficult trouble is urls with queries that have characters not allowed to be url-encoded.
Working url for URL-request http://www.bbc.co.uk/news/education-23809095#sa-ns_mchannel=rss&ns_source=PublicRSS20-sa
'#' character will replaced to "%23" by "stringByAddingPercentEscapesUsingEncoding:" method and will not work. Site will say what page not found. I believe after '#' character is a query string.
Are there a way to get(encode) any url from feeds correctly, at least always removing a query strings from xml?
There two approaches you could use to create a legal URL string by either using stringByAddingPercentEncodingWithAllowedCharacters or by using CFURL core foundation class which gives you a whole range of options.
Example 1 (NSCharacterSet):
NSString *nonFormattedURL = #"http://www.bbc.co.uk/news/education-23809095#sa-ns_mchannel=rss&ns_source=PublicRSS20-sa";
NSLog(#"%#", [nonFormattedURL stringByAddingPercentEncodingWithAllowedCharacters:[[NSCharacterSet illegalCharacterSet] invertedSet]]);
This still keep the hash tag in place by inverting the illegalCharacterSet in NSCharacterSet object. If you like more control you also create your own mutable set.
Example 2 (CFURL.h):
NSString *nonFormattedURL = #"http://www.bbc.co.uk/news/education-23809095#sa-ns_mchannel=rss&ns_source=PublicRSS20-sa";
CFAllocatorRef allocator = CFAllocatorGetDefault();
CFStringRef formattedURL = CFURLCreateStringByAddingPercentEscapes(allocator,
(__bridge CFStringRef) nonFormattedURL,
(__bridge CFStringRef) #"#", //leave unescaped
(__bridge CFStringRef) #"", // legal characters to be escaped like / = # ? etc
NSUTF8StringEncoding); // encoding
NSLog(#"%#", formattedURL);
Does the same as above code but with way more control: replacing certain characters with the equivalent percent escape sequence based on the encoding specified, see logs for example.
Basically I did this and I got an error:
NSString *searchWord = #"Lilwayne";
NSString *resourceURL = (#"https://api.soundcloud.com/tracks?client_id=546952635e22cc0182d85daceff34381&q=%#&format=json", searchWord);
Error is:
reason: 'Resource 'Lilwayne' is invalid because the scheme is not 'https'.'
I don't understand why this doesn't work. However if I remove the "%#" and replace it with "Lilwayne" it works.
The reason why I am doing it this way is because I have a search feature in my app to search for songs using the soundcloud sdk and I want to dynamically change the value of the variable "searchword" to whatever the user typed in.
Try to use stringWithFormat
NSString *resourceURL = [NSString stringWithFormat:#"https://api.soundcloud.com/tracks?client_id=546952635e22cc0182d85daceff34381&q=%#&format=json", searchWord];
I suggest a trip to the NSString class reference in the Xcode help system. In addition to stringWithFormat, as suggested by Basheer, There is a section on combining strings.
I have a web server which I used to fetch some data in my iOS application. The data include a field as the itemId let say '48501' (with no quotation). I read item JSON data into my itemObject in which itemId is defined as a NSString and not a NSInteger.
Everything works until this point but I have problems where I want to compare itemObject.itemId using isEqual: function with another NSString filled with 48501.
In other words both string are exactly the same and include 48501 when I print them. No space and hidden things is there. All isEqual: and isEqualToString: and == report false on comparison.
On the hand when I convert NSStrings to NSIntegers and compare them it works but not always! sometime TRUE sometime CRASH with no error to catch and just pointing to the line! I see them printed exactly the same but the if statement does not go through.
I showed the code to someone with far more experience than me and he was like this could be a bug! Anyone has ever exposed to this?
If your itemId is 48501 without any quotation in the JSON, then it's deserialized as NSNumber. Probably that's the problem in the first place. Try logging the type of your itemId and use appropriately -isEqualToString: for NSString and -isEqualToNumber: for NSNumber.
I'm confused. I'm parsing json string.
Before parsing, I check what is the content of the NSString.
In Xode4:
When I click on the NSString variable "print description"
The console show the value as \u434 \u433 format of the UTF-8
When I call NSLog("%#",content) the console show the "readble" character of the UTF-8 encoding.
Why is this different? How can I know that the string I got to parse is 100% UTF-8 ?
Thanks.
If you can see the Cyrillic characters you're looking for, rather than the escapes, through any method, then you're working with a UTF-8 string.
The "-description" method is not what you want to use here. It's more likely to show escaped characters; in particular, any time you store a value in a property list item like an NSArray or NSDictionary, its -description will generally escape any characters other than plain ASCII.
NSLog is a more reliable guide, because it doesn't use -description. If it's showing up in NSLog, it's probably just fine.
If you want to be absolutely sure your string is properly encoded UTF-8, the best way to test it is to display it. Create a text interface element (an NSTextField or UITextField) in your user interface, wire it up, and set your string as the value. If it displays there, it is properly formatted.
Short version: if it shows up in the debugger as escaped characters, it doesn't necessarily mean it's not UTF8. If it's showing up anywhere (including NSLog) with the proper characters, it's probably in the proper encoding. If you want to be sure, set up a test interface element and see how it looks there.