[摘要]本文是對XML數據解析(系統方法)的講解，對學習IOS蘋果軟件開發有所幫助,與大家分享。

XML是一種自描述的數據交換格式。是一種非常重要的數據交換 格式,多年來一直用於各種計算機語言中。XML類似HTML,有一對對標簽對,格式比HTML嚴謹,一個<>開始,一個</>結尾.

解析的內容為:

<users>
    <user id="001">
        <name>張三</name>
        <password>123456</password>
        <nickname>小張</nickname>
        <description>1111111111</description>
    </user>
    
    <user id="002">
        <name>張三</name>
        <password>2222222</password>
        <nickname>小四兒</nickname>
        <description>李四是個好學生</description>
    </user>
    
    <user id="003">
        <name>張三</name>
        <password>88888888</password>
        <nickname>小五</nickname>
        <description>1234567890</description>
    </user>
    
</users>

事先已將數據讀取並存儲在data中.
創建一個類,繼承自NSObject,命名為userInfo

@property(nonatomic,copy)NSString *uID;
@property(nonatomic,copy)NSString *name;
@property(nonatomic,copy)NSString *password;
@property(nonatomic,copy)NSString *nickname;
@property(nonatomic,copy)NSString *description;

再創建一個類,同樣繼承自NSObject,命名為userParser,實現xml文件的讀取.

userParser.h

#import <Foundation/Foundation.h>
#import "user.h"
@interface userParser : NSObject<NSXMLParserDelegate>
//存儲信息的數組
@property(nonatomic,retain)NSMutableArray *array;
//實例
@property(nonatomic,retain)user *people;
//創建字符串保存信息
@property(nonatomic,copy)NSMutableString *buffer;
//讀取xml文件
-(void)parserWithString:(NSString *)string;
@end

userparser.m

#import "userParser.h"

@implementation userParser
-(void)parserWithString:(NSString *)string
{
    //使用系統XML解析方法
    NSXMLParser *parser=[[NSXMLParser alloc]initWithData:[string dataUsingEncoding:NSUTF8StringEncoding]];
    //設置代理
    parser.delegate=self;
    //開始解析
    [parser parse];
}
#pragma mark ---NSXMLParserDelegate---
//開始解析
- (void)parserDidStartDocument:(NSXMLParser *)parser
{
    NSLog(@"it begin");
}
//解析結束
- (void)parserDidEndDocument:(NSXMLParser *)parser
{
    NSLog(@"it is over");
    for (int i=0; i<_array.count; i++) {
        user *user=_array[i];
        NSLog(@"%@,%@,%@,%@,%@",user.uID,user.name,user.password,user.nickname,user.description);
    }
}
//遇到開始標簽
//attributeDict標簽屬性
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{
    if ([elementName isEqualToString:@"users"]) {
        _array=[[NSMutableArray alloc]init];
    }
    else if ([elementName isEqualToString:@"user"])
    {
        _people=[[user alloc]init];
        //<user id="3">
        _people.uID=[attributeDict objectForKey:@"id"];
    }
    else if ([elementName isEqualToString:@"name"])
    {
        _buffer=[[NSMutableString alloc]init];
    }
    else if ([elementName isEqualToString:@"password"])
    {
        _buffer=[[NSMutableString alloc]init];
    }
    else if ([elementName isEqualToString:@"nickname"])
    {
        _buffer=[[NSMutableString alloc]init];
    }
    else if ([elementName isEqualToString:@"description"])
    {
        _buffer=[[NSMutableString alloc]init];
    }
    
}
//結束標簽
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
    if ([elementName isEqualToString:@"name"]) {
        _people.name=_buffer;
    }
    else if ([elementName isEqualToString:@"password"])
    {
        _people.password=_buffer;
    }
    else if ([elementName isEqualToString:@"nickname"])
    {
        _people.nickname=_buffer;
    }else if ([elementName isEqualToString:@"description"])
    {
        _people.description=_buffer;
    }
    else if ([elementName isEqualToString:@"user"])
    {
        [_array addObject:_people];
    }
}
//讀取內容
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
    //NSCharacterSet字符串結合,取出字符串中的空格
    [_buffer appendString:[string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]];
}

在viewcontroller中,創建userparser的實例對象,通過parserWithString方法實現數據解析

userParser *uparser=[[userParser alloc]init];
[uparser parserWithString:user];

注:將數據解析與界面顯示分開寫有助於減低程序的耦合,同時也符合MVC編程模式.