I am trying to use NSScanner is an NSArray enumeration loop. This however fails:
-[NSXMLElement length]: unrecognized selector sent to instance 0x280da30
No, I am not calling length anywhere. It seems like the value of found gets changed before the scanner completes, hence making it blank, causing the length error.
If I remove the loop and hardcode the string (i don't want that, it's just a test) the code below works. (excluding the enumeration of course)
It never gets as far as calling the NSLogs either...
Here's my code:
for (NSString*found in arr)
{
NSLog(#"Found %#",found);
NSString*search = [NSString stringWithString:found];
NSString *separatorString = #"\"";
NSString *container = nil;
NSScanner *aScanner = [NSScanner scannerWithString:search];
[aScanner setScanLocation:0];
[aScanner scanUpToString:#"src=\"" intoString:nil];
[aScanner scanString:#"src=\"" intoString:nil];
[aScanner scanUpToString:separatorString intoString:&container];
NSLog(#"scanned");
NSLog(#"%#",container);
NSImage*previewImage = [[NSImage alloc] initWithContentsOfFile:[relativeDir stringByAppendingPathComponent:container]];
[preview setImage:previewImage];
[previewImage release];
progressed = progressed + 1;
[convertProgress setDoubleValue:[convertProgress doubleValue] + progressed];
}
How can I get this to work?
Edit:
Here's the input:
NSXMLDocument*doc = [[NSXMLDocument alloc] initWithData:[NSData dataWithContentsOfFile:webPath] options:NSXMLDocumentTidyHTML error:nil];
NSArray*arr = [doc nodesForXPath:#"//img[#src]" error:nil];
From the documentation:
The nodesForXPath:error: method
returns an array of NSXMLNode objects
Your array is not full of strings. It is full of various NSXML* objects. They aren't garbage. This is exactly how it is supposed to work.
You may not be calling length, but stringWithString: is probably calling length to figure out how much space to allocate in the new string.
Conversion to a string can mean a lot of things. An XML node may be a standalone tag, it may be some inline CDATA, it may be a tag with various attributes. As well, an XML document is highly structured. It is rarely meaningful to walk through the contents of a document as a straight enumeration of tags/contents without applying some amount of structural meaning.
You are likely going to need to recurse or otherwise walk the tags and interpret their contents appropriately.
The first step would be to remove everything but that initial NSLog() and see what you got. Then figure out how to walk the tree of nodes. Then figure out how to parse 'em appropriately.
Are you sure that your arr contains NSString objects? The fact that NSXMLElement is throwing an error looks fishy to me.
Edit
Yep, looks like the docs say the array from nodesForXPath doesn't contain NSString objects, but NSXMLElement objects.
http://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSXMLNode_Class/Reference/Reference.html#//apple_ref/occ/instm/NSXMLNode/nodesForXPath:error:
Related
The goal is to have an array where all strings are of length n.
So at the moment what I have my code doing is reading in a plist (which is just 250,000 strings) into an array, and then iterating over the array in order to find which ones are/aren't of length n. Of course, for the sake of efficiency, I'd prefer being able to read in from the plist STRING BY STRING so, as I'm reading in, I may the length then before inserting into the array. I'm just starting to learn objective-c, but I was struggling to Google around for a solution =P
EDIT: Well I just found out I can find much more documentation typing property list rather than plist into google :) so I may be able to figure this out myself
You can parse plist into tree (NSMutableDictionary). Dict will have keys with name of string length.
for example
NSMutableDictionary *result = [NSMutableDictionary dictionary];
for (NSString *str in [plistDict allObjects]) {
NSString *key = [NSString stringWithFormat:#"%d", [str length]];
NSMutableArray *array = [result objectForKey:key];
if (!array) {
array = [NSMutableArray array];
}
[array addObject:str];
[result setObject:array forKey:key];
}
than you can access array with needed strings length
NSArray *string4Lenght = [result objectForKey:#"4"];
Apple doesn't provide an API for incrementally parsing a plist.
If you store your plist in XML format, you could use NSXMLParser to parse it. The schema is pretty simple and somewhat described in the Property List Programming Guide.
If you want to incrementally parse the binary format, you're going to have to do more work. There's no official documentation for the format. Apple's source code for reading and writing the format is open source (CFBinaryPList.c) and there are some useful comments along with the actual code.
If you really need to do it incrementally, I suggest going the XML route. If you do, you might want to subclass NSInputStream to be able to read from a gzip or bzip2 file and decompress on the fly.
I am work on a simple program in which I split a string and a user global, I use the following code for splitting the string.
NSString *GlobleStr;//globale variable
//===============
NSString *xmlParsingResult=#"Apple,iphone";
NSArray *array = [xmlParsingResult componentsSeparatedByString:#","];
NSString *StrResult = [NSString stringWithFormat:#"%#", [array objectAtIndex:0]];
GlobleStr =[NSString stringWithFormat:#"%#",[array objectAtIndex:1]];
NSLog(#"cmd %#",StrResult);
NSLog(#"value%#",GlobleStr);
my code can split the string and o/p is cmd:Apple value:iphone
but my problem is that as soon as I call another xib then my global variable will be empty or nil and the application will crash ( it throws error like Variable is not cfstring).
Any suggestions?
It's because NSString's +stringwithFormat: method returns an autoreleased string. In a local variable this is often what you want to prevent memory leaks (otherwise you have to manually release the string when you're done with it). The problem here is that the string in GlobleStr is getting released by the autorelease pool sometime after you assign it, then when you try to access it in another place you get a crash.
The fix is this: GlobleStr = [[NSString stringWithFormat:#"%#",[array objectAtIndex:1]] retain];
As an aside, you can just do this instead:
GlobleStr = [[array objectAtIndex:1] retain];
I strongly recommend reading Apple's documentation regarding memory management in Cocoa: http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/MemoryMgmt/MemoryMgmt.html .
Finally, without seeing your code I can't say for sure, but I'd be curious to know why you're using a global variable for GlobleStr. It's a blanket statement, and there are certainly exceptions, but when programming in Cocoa there's probably a better way to structure your code.
You need to retain your global, otherwise it will be deallocated when the autorelease pool drains:
GlobleStr = [[NSString stringWithFormat:#"%#", [array objectAtIndex:0]] retain];
Remember to release it later on when you're done -- in particular, before assigning any other value to it.
URL Download
http://code.google.com/p/mwiphonesdk/source/browse/#svn/trunk/iMADE/PrepTasks/08
I have code at the location at the link above and I am using NSMutableString to append strings as data is downloaded. But I am finding that using appendString does not increase the length of the mutable string. I must be doing something wrong.
And when I am done I need to convert NSMutableString to NSString to return it. I have looked for examples to do this but I do not see any yet.
I am most familiar with Java and C# where there is a StringBuffer/StringBuilder which allows you to append pieces and them simply call toString at the end to get a String. It does not appear to be this easy in Objective-C.
NSString* str = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
#pragma mark TODO Confirm this is appending a value to the mutable string
[self.mutableString appendString:str];
NSLog(#"str length: %d, %d", [str length], [self.mutableString length]);
Above is the section of code that calls appendString.
I see that str has a length > 0 but calling appendString does not increase the length of self.mutableString.
What am I doing wrong here?
As for having an NSMutableString* and needing to return an NSString*, the former is a subclass of the latter so anywhere you see an NSString* an NSMutableString* will suffice as-is.
Your code looks OK from what you've posted. The only thing I can think of is that perhaps there isn't any data to speak of when initializing the str variable. In such a case appending an empty string will do nothing to mutableString.
You'll also want to make sure self.mutableString has been properly allocated and initialized. You can send messages to NSObject*s that are nil which may be misleading when [self.mutableString length] returns 0.
I have fixed the problem. I simply was not initializing the NSMutableString value and it was transparently not doing anything.
Before appending the string I put the following code.
if (_mutableString == nil){
_mutableString = [[NSMutableString alloc] init];
}
Thanks everyone for answering. And it is good to know that I can use NSMutableString in place of NSString. (that is too easy) :)
i've written a for loop in Objective-C, This is how my code looks like
NSString *string = [NSString stringWithContentsOfFile=#"/Users/Home/myFile.doc"];
NSString *seperator=#"\n";
NSArray *mainarray = [string componentsSeparatedByString:seperator];
// Since i want to parse each element of mainarray
for(NSString *s in mainarray)
{
//again parising the string using a new separator
NSString newseparator = #"=";
NSArray *subarray = [s componentsSeparatedByString : newseparator];
//Copying the elements of array into key and object string variables
NSString *key = [subarray objectAtIndex:0];
NSLog(#"%#",key);
NSString *class_name= [subarray objectAtIndex:1];
NSLog(#"%#",class_name);
// create an instance for the class_name
//dont knw how it ll take the value from file and ???
//Putting the key and objects values into hashtable
NSMutableDictionary = [NSDictionary dictinaryWithObject:class_name forKey:key];
}
Whenever i execute this code this crashes my program saying as, Terminating the app due to uncaught exception NSRangeException
How to know the range of array and how to specify the terminating condition in the for loop???and plz let me knw how to handle this exception???
I'm surprised that code even compiles. If I remember correctly, it can't compile unless you have gone to great lengths to turn off a whole bunch of compiler warnings.
NSString newseparator = #";";
That should give an error write there in that you don't have the *.
NSString *key = [subarray objectAtIndex[0]];
NSString *object = [subarray objectAtIndex[1]];
Neither of these lines of code make any sense.
It would appear that you haven't posted the actual code?
Now, getting back to the exception. A range exception will be tossed if you try to access an item at an index that is outside of the range of indexes available in the array. Thus, if componentsSeparatedByString: returned an array of 0 or 1 elements, then [subarray objectAtIndex: 1]; will cause a range exception to be raised.
What you don't want to do is to try and handle the exception using an #catch block. In Cocoa (and iPhone development), exceptions are treated as non-recoverable errors.
So, instead, use the -count method on NSArray to verify that the array actually contains the # of elements you were expecting. Since you are writing a casual parser, this is probably a good idea as a minimal check of input validity.
I have to parse an XML file using NSXMLParser. There are so many HTML tags in them, so when I am trying to parse it, it will store the string up to that and then again go to found character method and starts to append it.
my code is:
if (Bio_CResults) {
[BioResults appendString: string];
[Info appendString:string];
[stringarr addobject:Info];
NSLog(#"bio==%#",BioResults);
NSLog(#"string==%#",string);
}
and I want to add it in string array, but here it will make create extra object of array. i.e.
stringarr objectAtIndex 0 = abc
stringarr objectAtIndex 1 = def
stringarr objectAtIndex 2 = ghi
but actually I want all of them together in one object because they are actually one string only..
plz help me for that
If you don't even need multiple string objects you can use an NSMutableString instead of an array. Just use the appendString: method to add to the end of the string:
NSMutableString *string = [NSMutableString string];
[string appendString:#"abc"];
[string appendString:#"def"];
NSLog(#"New string is %#", string);
This will log "New string is abcdef".
If you really want an array, use an NSMutableArray instead of an NSArray. That way you can change an object in-place (replace a string with a new string created by appending another string). So for example:
// First create an array with #"abc"
NSMutableArray *mArray = [NSMutableArray arrayWithObject:#"abc"];
// Next get the first object as a string and append #"def" to it in-place
NSString *string = (NSString *)[mArray objectAtIndex:0];
[mArray replaceObjectAtIndex:0 withObject:[string stringByAppendingString:#"def"]];
// Now get the new first object
NSLog(#"First object is %#", (NSString *)[mArray objectAtIndex:0]);
This will log the message "First object is abcdef".
I really dont like NSXmlParser. You might want to read my blog post on using RegxKitLite
http://blog.bluespark.co.nz/?p=51
It might be of some help. Hopefully it wont lead you in the wrong direction.
Cheers, John.
There are so many HTML tags in them…
Be aware that HTML is usually not valid XML. If you're parsing HTML, an XML parser will throw an error some part of the way through the document.
You may be better off creating a WebView, loading the HTML content into it, and then getting a DOMDocument from the view's main frame and traversing the DOM hierarchy. You don't have to put the view into a window; you can just use it to get a DOMDocument.
If you are parsing XML and meant to say “XML tags”, you can disregard this answer.