XML阅读器类中新的线条和空格 [英] Pesky new lines and whitespace in XML reader class

问题描述

我正在使用一个由博客写的课程（ http://troybrant.net/blog/ ）字符串并吐出一个NSDictionary。

I'm using a class written by a blogger (http://troybrant.net/blog/) that takes an XML string and spits out a NSDictionary.

它很漂亮......完美无缺，除了我在许多元素值的开头有一个奇怪的换行符和空白区域。

It's beautiful...works perfectly, except I end up with a weird configuration of newlines and white space at the beginning of many element values.

我一直无法弄明白为什么。我在这里上课，所以我可以得到第二双眼睛...看看是否有人注意到他正在使用的方法中有任何可疑的东西。

I haven't been able to figure out why. I'm posting the class here so I can get a second pair of eyes...see if anyone notices anything suspect in the method he is using.

//
//  XMLReader.m
//

#import "XMLReader.h"

NSString *const kXMLReaderTextNodeKey = @"text";

@interface XMLReader (Internal)

- (id)initWithError:(NSError **)error;
- (NSDictionary *)objectWithData:(NSData *)data;

@end


@implementation XMLReader

#pragma mark -
#pragma mark Public methods

+ (NSDictionary *)dictionaryForXMLData:(NSData *)data error:(NSError **)error
{
    XMLReader *reader = [[XMLReader alloc] initWithError:error];
    NSDictionary *rootDictionary = [reader objectWithData:data];
    [reader release];
    return rootDictionary;
}

+ (NSDictionary *)dictionaryForXMLString:(NSString *)string error:(NSError **)error
{
    NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];
    return [XMLReader dictionaryForXMLData:data error:error];
}

#pragma mark -
#pragma mark Parsing

- (id)initWithError:(NSError **)error
{
    if ((self = [super init]))
    {
        errorPointer = error;
    }
    return self;
}

- (void)dealloc
{
    [dictionaryStack release];
    [textInProgress release];
    [super dealloc];
}

- (NSDictionary *)objectWithData:(NSData *)data
{
    // Clear out any old data
    [dictionaryStack release];
    [textInProgress release];

    dictionaryStack = [[NSMutableArray alloc] init];
    textInProgress = [[NSMutableString alloc] init];

    // Initialize the stack with a fresh dictionary
    [dictionaryStack addObject:[NSMutableDictionary dictionary]];

    // Parse the XML
    NSXMLParser *parser = [[NSXMLParser alloc] initWithData:data];
    parser.delegate = self;
    BOOL success = [parser parse];

    // Return the stack's root dictionary on success
    if (success)
    {
        NSDictionary *resultDict = [dictionaryStack objectAtIndex:0];
        return resultDict;
    }

    return nil;
}

#pragma mark -
#pragma mark NSXMLParserDelegate methods

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{
    // Get the dictionary for the current level in the stack
    NSMutableDictionary *parentDict = [dictionaryStack lastObject];

    // Create the child dictionary for the new element, and initilaize it with the attributes
    NSMutableDictionary *childDict = [NSMutableDictionary dictionary];
    [childDict addEntriesFromDictionary:attributeDict];

    // If there's already an item for this key, it means we need to create an array
    id existingValue = [parentDict objectForKey:elementName];
    if (existingValue)
    {
        NSMutableArray *array = nil;
        if ([existingValue isKindOfClass:[NSMutableArray class]])
        {
            // The array exists, so use it
            array = (NSMutableArray *) existingValue;
        }
        else
        {
            // Create an array if it doesn't exist
            array = [NSMutableArray array];
            [array addObject:existingValue];

            // Replace the child dictionary with an array of children dictionaries
            [parentDict setObject:array forKey:elementName];
        }

        // Add the new child dictionary to the array
        [array addObject:childDict];
    }
    else
    {
        // No existing value, so update the dictionary
        [parentDict setObject:childDict forKey:elementName];
    }

    // Update the stack
    [dictionaryStack addObject:childDict];
}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
    // Update the parent dict with text info
    NSMutableDictionary *dictInProgress = [dictionaryStack lastObject];

    // Set the text property
    if ([textInProgress length] > 0)
    {
        [dictInProgress setObject:textInProgress forKey:kXMLReaderTextNodeKey];

        // Reset the text
        [textInProgress release];
        textInProgress = [[NSMutableString alloc] init];
    }

    // Pop the current dict
    [dictionaryStack removeLastObject];
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
    // Build the text value
    [textInProgress appendString:string];
}

- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError
{
    // Set the error pointer to the parser's error object
    *errorPointer = parseError;
}

@end

如果这是一个烦人的问题，我道歉（请不要怨恨我）。我只想弄清楚这里发生了什么，缺乏自己找到的编码能力。 （我是Obj-C的新手）

If this is an annoying question, I apologize (and please don't vote me down out of spite). I'm just trying to figure out what's going on here and lack of the coding prowess to find it myself. (I'm new to Obj-C)

Clif

解决方案：

更改此行：

[dictInProgress setObject:textInProgress forKey:kXMLReaderTextNodeKey];

到此行：

[dictInProgress setObject:[textInProgress stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] forKey:kXMLReaderTextNodeKey];

推荐答案

您可以修剪从该课程中获得的值：

You could trim the values you get out of that class:

NSString *trimmedValue = [value stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

这将删除前导和尾随空格。

That would remove leading and trailing white space.

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