從Objective-C的

Question

瀏覽XML我從TwitPic得到這個XML響應：

 <?xml version="1.0" encoding="UTF-8"?> 
    <rsp stat="ok"> 
     <mediaid>abc123</mediaid> 
     <mediaurl>http://twitpic.com/abc123</mediaurl> 
    </rsp> 

我想將 'mediaurl' 標籤中訪問值。

所以，我想：

NSString *twitpicURL = [[request responseHeaders] objectForKey:@"mediaurl"]; 

但是，這似乎並沒有工作。

有人可以用這個指向我的正確方向嗎？

謝謝，

傑米。

Answer 1

CoreFoundation有一個用於解析xml的庫。

http://developer.apple.com/documentation/CoreFoundation/Conceptual/CFXML/CFXML.html

，如果你不爲蘋果平臺開發，外籍人士是一個衆所周知的çXML解析器:)

http://expat.sourceforge.net/

Answer 2

蘋果NSXMLDocument（適用於僅適用於Mac OS X）和NSXMLParser（適用於Mac OS X和iPhone）均基於開源C庫Libxml2（可在Mac OS X和iPhone上使用）。

如果您決定使用NSXMLDocument，我會建議使用XPath作爲快速/簡單的方式來獲取數據。

Answer 3

我意識到你在幾天前問過這個問題，但我想我會給你一個如何使用NSXMLParser的例子。我不記得我從哪裏學到這些，但這是我在項目中使用的技術。

您可以創建自己的類，像這樣創建自己的類並在網絡調用結束後實例化它並調用「parseData：」函數，或者將所有這些mumbo jumbo粘貼到處理網絡代碼的類中並調用函數從那裏。

#import "ThaweExampleParser.h" 

@interface ThaweExampleParser() <NSXMLParserDelegate> 
@property (nonatomic) BOOL accumulatingParsedCharacterData; 
@property (nonatomic, strong) NSMutableString *currentParsedCharacterData; 
@property (nonatomic, strong) NSMutableDictionary *parsedContents; 
@end 

@implementation ThaweExampleParser 

@synthesize accumulatingParsedCharacterData; 
@synthesize currentParsedCharacterData; 
@synthesize parsedContents; 

/* 
* This function you would call when your network connection finishes. 
* You pass in the NSMutableData you collected during the request. 
*/ 

- (void)parseData:(NSData *)webData 
{ 
    self.currentParsedCharacterData = [NSMutableString string]; 
    self.parsedContents = [NSMutableDictionary dictionary]; 
    NSXMLParser *parser = [[NSXMLParser alloc] initWithData:webData]; 
    parser.delegate = self; 
    [parser parse]; 
} 

/* 
* The parsed calls this function everytime it finds a new tag. 
* A tag looks like "<mediaurl>" 
* So in this case we want to turn or BOOL to YES so that the last function collects only the characters we care about. 
*/ 

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict 
{ 
    if ([elementName isEqualToString:@"mediaurl"]) 
    { 
     self.accumulatingParsedCharacterData = YES; 
     [self.currentParsedCharacterData setString:@""]; 
    } 
} 

/* 
* Much the previous function except the tag looks like "</mediaurl>" 
* Turn our BOOL to NO because we are done collecting characters for the moment. 
* We also are saving the important data to a dictionary so that you can use it later. 
*/ 

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName 
{ 
    if ([elementName isEqualToString:@"mediaurl"]) 
    { 
     self.accumulatingParsedCharacterData = NO; 
     [self.parsedContents setObject:[self.currentParsedCharacterData copy] forKey:elementName]; 
    } 
} 

/* 
* The parser calls this function everytime it finds characters. 
* In your case it would call it maybe 5 or 6 times with data that you dont want to collect. 
* So we use a BOOL to control what we collect; 
*/ 

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string 
{ 
    if (self.accumulatingParsedCharacterData) [self.currentParsedCharacterData appendString:string]; 
} 

@end