I'm having a problem with creating an NSURL object using an URL string which looks like this:
"... fexp=935648%2C945012%2C901066%2C91 ..." and so on (it's just a part - the complete URL is very long).
The URL contains many percentage escaped characters (%2C). I am absolutely not able to create an NSURL object with this URL (the URL itself is correct, as I can open it using a browser). The call to
[[NSURL alloc] initWithString:url];
returns NIL.
As soon as I modify the url by calling
[url stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]
I receive a valid NSURL object.
Problem is: this "valid" NSURL object contains an invalid URL which looks like this:
"... fexp=935648%252C945012%252C901066%225C91 ..."
As you can see the initial percent escaped character (%2C) has been escaped again (%252C) which results in an URL which cannot be opened (tried it using a browser again).
The original URL is generated by an external tool so I don't have any influence on its creation mechanism.
Does anybody have a clue what might be wrong?
To me it seems a little bit strange but the following seems to work:
[url stringByRemovingPercentEncoding];
[url stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];`
Thanks for the hints.
Related
Hi I saved a URL that has a path to a directory where I will be storing information, Now I want to retrieve the information but I don't know how to receive the items, I am trying to use initWithContentsOfURL but I dont know what the encoding would be?
This is how I saved the URL
//DirectoryPaths has the NSCAcheDirectory
dirPath = [[directoryPaths objectAtIndex:0] URLByAppendingPathComponent:[NSString stringWithFormat:#"photos.jpg"]];
How do I get a path to the URL now? I tried
NSString *pathToFile = [[NSString alloc] initWithContentsOfURL:dirPath
usedEncoding:nil
error:&error];
I have no clue what the encoding would be since I didnt use one to store the file?
I think you've misunderstood; initWithContentsOfURL:usedEncoding:error: loads a string from a URL. So you'd specify the encoding used for the string — UTF-8, ASCII or something like that.
To get a disk path from a URL you probably want [dirPath path]. In practice you can probably just load from the URL rather than hardcoding local disk behaviour.
Use NSUTF8StringEncoding or ASCII. It works for me. :)
I've read the documentation, and it looks like some edge cases might be different (trailing slashes, etc.), but it's not clear to me what the main difference between these two method is. Do the terms Component and Extension have special meaning in the URL world that people other than me understand?
The path extension is for adding things like .html to the URL, and the path component is for adding things like /news/local. The documentation for path extension:
If the original URL ends with one or more forward slashes, these are removed from the returned URL. A period is inserted between the two parts of the new URL.
So http://hello.com/news/ would become http://hello.com/news.html
The docs for path component:
If the original URL does not end with a forward slash and pathComponent does not begin with a forward slash, a forward slash is inserted between the two parts of the returned URL, unless the original URL is the empty string.
So http://hello.com/news/ would become http://hello.com/news/html
Here's a quick test:
NSURL *originalURL = [NSURL URLWithString:#"http://hello.com/news"];
NSLog(#"%#", [originalURL URLByAppendingPathComponent:#"local"]);
NSLog(#"%#", [originalURL URLByAppendingPathExtension:#"local"]);
Output:
http://hello.com/news/local
http://hello.com/news.local
Whenever I have questions about things like this, and the documentation is not helping, I just test it in a logic test.
NSURL *baseURL = [NSURL URLWithString:#"http://foo.com/bar/baz"];
NSURL *appendExtension = [baseURL URLByAppendingPathExtension:#"qux"];
NSURL *appendComponent = [baseURL URLByAppendingPathComponent:#"qux"];
STAssertEqualObjects([appendExtension absoluteString], #"http://foo.com/bar/baz.qux", nil);
STAssertEqualObjects([appendComponent absoluteString], #"http://foo.com/bar/baz/qux", nil);
So there it is, an extension is the .(file-type) there component is /(directory).
I am converting the response data from a web request to an NSString in the following manner:
NSData *data = self.responseData;
if (!data) {
return nil;
}
NSStringEncoding encoding = CFStringConvertEncodingToNSStringEncoding(CFStringConvertIANACharSetNameToEncoding((__bridge CFStringRef)[self.response textEncodingName]));
NSString *responseString = [[NSString alloc] initWithData:data encoding:encoding];
However the resulting string looks like this:
"birthday":"04\/01\/1990",
"email":"some.address\u0040some.domain.com"
What I would like is
"birthday":"04/01/1990",
"email":"some.address#some.domain.com"
without the backslash escapes and unicode. What is the cleanest way to do this?
The response seems to be JSON-encoded. So simply decode the response string using a JSON library (SBJson, JsonKit etc.) to get the correct form.
You can replace (or remove) characters using NSString's stringByReplacingCharactersInRange:withString: or stringByReplacingOccurrencesOfString:withString:.
To remove (convert) unicode characters, use dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES (from this answer).
I'm sorry if the following has nothing to do with your case: Personally, I would ask myself where did that back-slashes come from in the first place. For example, for JSON, I'd know that some sort of JSON serializer on the other side escapes some characters (so the slashes are really there, in the response, and that is not a some weird bug in Cocoa). That way I'd able to tell for sure which characters I have to handle and how. Or maybe I'd use some kind of library to do that for me.
I have a Mac application that keeps it's own log file. It appends info to the file using NSString's writeToFile method. One of the things that it logs are URL's of web services that it is interacting with. To encode the URL, I'm doing this:
searchString = (NSString *)CFURLCreateStringByAddingPercentEscapes(NULL, (CFStringRef)searchString, NULL, (CFStringRef)#"!*'();:#&=+$,/?%#[]", kCFStringEncodingUTF8 );
The app then appends searchString to the rest of the URL and writes it to the log file. Now the problem is that after adding that URL encoding line, nothing seems to be getting written to the file. The program functions as expected otherwise however. Removing the line of code above results in all of the correct information being logged to the file (removing that line is not an option because searchString must be URL encoded).
Oh and I am using NSUTF8StringEncoding when writing the NSString to the file.
Thanks for any help.
EDIT: I know there's also a similar function to CFURLCreateStringByAddingPercentEscapes in NSString, but I've read that it doesn't always work. Can anyone shed some light on this if my original question cannot be answered? Thanks! (EDIT: same problem occurs when using stringByAddingPercentEscapesUsingEncoding:)
EDIT 2: Here's the code that I'm using to append messages to the log file.
+(void)logText:(NSString *)theString{
NSString *docsDirectory = [NSSearchPathForDirectoriesInDomains(NSApplicationSupportDirectory,NSUserDomainMask,YES) objectAtIndex:0];
NSString *path = [docsDirectory stringByAppendingPathComponent:#"Folder/File.log"];
NSString *fileContents = [[[NSString alloc] initWithContentsOfFile:path] autorelease];
if([fileContents lengthOfBytesUsingEncoding:NSUTF8StringEncoding] >= 204800){
fileContents = #"";
}
NSString *timeStamp = [[NSDate date] description];
timeStamp = [timeStamp stringByAppendingString:#": "];
timeStamp = [timeStamp stringByAppendingString:theString];
fileContents = [fileContents stringByAppendingString:timeStamp];
fileContents = [fileContents stringByAppendingString:#"\n"];
[fileContents writeToFile:path atomically:YES encoding:NSUTF8StringEncoding error:NULL];
}
Because after almost a whole day no one else has offered any answers, I'm going to post a wild guess here: you're not accidentally using the string you want to output (with percent characters in it) as a format string are you?
That is, making the mistake of doing:
NSLog(#"In format strings you can use %# as a placeholder for an object, and %i for a plain C integer.")
Instead of:
NSLog(#"%#", #"In format strings you can use %# as a placeholder for an object, and %i for a plain C integer.");
But I'm going to be surprised if this turns out to be the cause of your problem, as it usually causes random-looking output, rather than absolutely no output. And in some cases, Xcode also gives compiler warnings about it (when I tried NSLog(myString), I got "warning: format not a string literal and no format arguments").
So don't shoot me down if this answer doesn't help. It would be easier to answer your question if you could show us more of your logging code. As for the one line you provided, I can't detect anything wrong with it.
Edit: Oops, I kind of missed that you mentioned you're using writeToFile:atomically:encoding:error: to write the string to the file, so it's even more unlikely you're accidentally treating it as a format string somewhere. But I'm going to leave this answer up for now. Again, you should really show us more of your code though ...
Edit: Regarding your question on a method in NSString that has similar percent encoding functionality, that would be stringByAddingPercentEscapesUsingEncoding:. I'm not sure what kind of problems you're thinking of when you say you've heard it doesn't always work. But one thing is that CFURLCreateStringByAddingPercentEscapes allows you to specify extra characters that don't normally have to be escaped but which you still want to be escaped, while the method of NSString doesn't allow you to specify this.
Is there some blindingly obvious reason why this is producing a nil string instead of the actual text content of the file?
NSString *fromFile = [NSString stringWithContentsOfFile:
#"file://localhost/Users/username/Desktop/test.txt"];
NSLog(#"%#", fromFile);
PRINTS: "(null)"
The file is a plain ASCII text file saved from TextWrangler with contents ' abc '.
The path comes from dragging the actual file from the desktop into the Xcode editor window.
I've also tried without "file://localhost".
The method documentation says "Returns nil if the file can't be opened". There's nothing unusual about the file (not locked, etc.). It has default Unix permissions and was created by the same user as is running Xcode.
I know this method is deprecated -- trying to get this working first.
You have stringWithContentsOfFile: and stringWithContentsOfURL: mixed up.
If you are passing in a URL e.g.
#"file://localhost/Users/username/Desktop/test.txt"
the you want stringWithContentsOfURL: and make the parameter a NSURL e.g.
[NSURL URLWithString:#"file://localhost/Users/username/Desktop/test.txt"]
If you want to use stringWithContentsOfFile: the the parameter should be
#"/Users/username/Desktop/test.txt"
Have you tried ~/Desktop/test.txt or /Users/username/Desktop/test.txt?