Ios教程網 >> IOS使用技巧 >> IOS技巧綜合 >> IOS 解析XML文檔

IOS 解析XML文檔

編輯：IOS技巧綜合

[摘要]本文是對IOS 解析XML文檔的講解，對學習IOS蘋果軟件開發有所幫助,與大家分享。

前段時間想找點事做，就是試著看能不能用豆瓣的API做點什麼，於是就碰到了這個問題——XML解析。

　　老師還沒講，只能自己去查。

　　XML文檔解析主要有SAX和DOM兩種模式，IOS上兩種模式都可以用，這裡就不做過多介紹，我選擇的SAX模式。

IOS解析XML用的是自帶的NSXML框架，框架的核心是NSXMLParser類和它的委托協議NSXMLParserDelegate，其主要的解析工作是在NSXMLParserDelegate實現類中完成的。委托中定義了許多回掉方法，在SAX解析器從上到下遍歷XML文檔的過程中，遇到開始標簽、結束標簽、文檔開始、文檔結束和字符串結束是就會觸發這些方法。這些方法有很多，下面我們列出5個常用的方法。

在文檔開始時觸發

 -(void)parserDidStartDocument:(NSXMLParser *)parser

　　遇到一個新標簽是觸發，其中namespaceURI是命名空間，qualifiedName是限定名，attributes是字典類型的屬性集合。

-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict

　　找到字符串時觸發

    -(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string

　　遇到結束標簽時觸發

    -(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName

　　在文檔結束時觸發

-(void)parserDidEndDocument:(NSXMLParser *)parser

下面通過一個具體的例子來看整個的調用與解析過程

首先這是我們將要解析的XML文件 "info.xml"

            <?xml version="1.0" encoding="UTF-8"?>

            <root>      

                 <person id="1">

                     <firstName>Wythe</firstName>
                   
                     <lastName>xu</lastName>
                   
                     <age>22</age>              

                 </person>
          
                <person id="2">
               
                     <firstName>li</firstName>
                    
                     <lastName>si</lastName>
                    
                     <age>31</age>
              
                 </person>
                
                    <person id="3">
                       
                     <firstName>Dipen</firstName>
                        
                     <lastName>Shah</lastName>
                        
                     <age>24</age>
                    
                 </person>
                
            </root>

接來來是一個頭文件 "ViewController.h"

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController<NSXMLParserDelegate>

@property NSXMLParser *parser;
@property NSMutableArray *person;
@property NSString *currenttag;

@end

然後是它的實現文件 "ViewController.m"

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

@synthesize  parser = _parser , person = _person , currenttag = _currenttag;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    NSString *xmlFilePath = [[NSBundle mainBundle]pathForResource:@"info"ofType:@"xml"];
    
    NSData *data = [[NSData alloc]initWithContentsOfFile:xmlFilePath];
    
    self.parser = [[NSXMLParser alloc]initWithData:data];
    
    self.parser.delegate = self;
    
    [self.parser parse];
    
    NSLog(@"%@",_person);
    
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark delegate method

-(void)parserDidStartDocument:(NSXMLParser *)parser
{
    _person = [[NSMutableArray alloc]init];
    NSLog(@"start parse 1");
}

-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{
    _currenttag = elementName;
    
    if ([_currenttag isEqualToString:@"person"]) {
        NSString *_id = [attributeDict objectForKey:@"id"];
        NSMutableDictionary *dict = [[NSMutableDictionary alloc]init];
        [dict setObject:_id forKey:@"id"];
        [_person addObject:dict];
    }
    
    NSLog(@"start element");
}

-(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
    NSMutableDictionary *dict = [_person lastObject];
    
    if ([_currenttag isEqualToString:@"firstName"] && dict) {
        [dict setObject:string forKey:@"firstName"];

    }
    if ([_currenttag isEqualToString:@"lastName"] && dict) {
        [dict setObject:string forKey:@"lastName"];
    }
    if ([_currenttag isEqualToString:@"age"] && dict) {
        [dict setObject:string forKey:@"age"];
    }
    
    NSLog(@"found characters");
}

-(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
    _currenttag = nil;
    
    NSLog(@"end element");
}

-(void)parserDidEndDocument:(NSXMLParser *)parser
{
    NSLog(@"parse end");
}
@end

通過斷電和輸出信息，我們可以知道整個解析過程是開始解析文檔、開始標簽、找到字符串、結束標簽、文檔結束。

2014-09-10 16:45:32.920 xmlforblog[3820:60b] start parse 1
2014-09-10 16:45:32.921 xmlforblog[3820:60b] start element
2014-09-10 16:45:32.922 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.922 xmlforblog[3820:60b] start element
2014-09-10 16:45:32.922 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.922 xmlforblog[3820:60b] start element
2014-09-10 16:45:32.923 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.923 xmlforblog[3820:60b] end element
2014-09-10 16:45:32.923 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.923 xmlforblog[3820:60b] start element
2014-09-10 16:45:32.924 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.924 xmlforblog[3820:60b] end element
2014-09-10 16:45:32.924 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.924 xmlforblog[3820:60b] start element
2014-09-10 16:45:32.925 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.925 xmlforblog[3820:60b] end element
2014-09-10 16:45:32.925 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.925 xmlforblog[3820:60b] end element
2014-09-10 16:45:32.926 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.926 xmlforblog[3820:60b] start element
2014-09-10 16:45:32.928 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.929 xmlforblog[3820:60b] start element
2014-09-10 16:45:32.929 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.929 xmlforblog[3820:60b] end element
2014-09-10 16:45:32.930 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.930 xmlforblog[3820:60b] start element
2014-09-10 16:45:32.930 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.930 xmlforblog[3820:60b] end element
2014-09-10 16:45:32.931 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.931 xmlforblog[3820:60b] start element
2014-09-10 16:45:32.931 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.931 xmlforblog[3820:60b] end element
2014-09-10 16:45:32.931 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.932 xmlforblog[3820:60b] end element
2014-09-10 16:45:32.932 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.932 xmlforblog[3820:60b] start element
2014-09-10 16:45:32.932 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.933 xmlforblog[3820:60b] start element
2014-09-10 16:45:32.933 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.933 xmlforblog[3820:60b] end element
2014-09-10 16:45:32.933 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.934 xmlforblog[3820:60b] start element
2014-09-10 16:45:32.934 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.934 xmlforblog[3820:60b] end element
2014-09-10 16:45:32.934 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.935 xmlforblog[3820:60b] start element
2014-09-10 16:45:32.935 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.935 xmlforblog[3820:60b] end element
2014-09-10 16:45:32.935 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.936 xmlforblog[3820:60b] end element
2014-09-10 16:45:32.936 xmlforblog[3820:60b] found characters
2014-09-10 16:45:32.936 xmlforblog[3820:60b] end element
2014-09-10 16:45:32.936 xmlforblog[3820:60b] parse end
2014-09-10 16:45:32.936 xmlforblog[3820:60b] (
        {
        age = 22;
        firstName = Wythe;
        id = 1;
        lastName = xu;
    },
        {
        age = 31;
        firstName = li;
        id = 2;
        lastName = si;
    },
        {
        age = 24;
        firstName = Dipen;
        id = 3;
        lastName = Shah;
    }
)

執行結果

而我們的處理主要是在開始標簽、找到字符串（

-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict

-(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string

）中。

遇到開始標簽時，我們現判斷標簽，名字，如果是person，表明接下來就是person的信息，這樣我們就先創建一個可變字典，以便將來存放它的值。

-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{
    _currenttag = elementName;
    
    if ([_currenttag isEqualToString:@"person"]) {
        NSString *_id = [attributeDict objectForKey:@"id"];
        NSMutableDictionary *dict = [[NSMutableDictionary alloc]init];
        [dict setObject:_id forKey:@"id"];
        [_person addObject:dict];
    }
    
    NSLog(@"start element");
}

在找到字符串時，我們就是通過判斷當前標簽名，將對應的信息保存到剛剛創建的字典中

-(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
    NSMutableDictionary *dict = [_person lastObject];
    
    if ([_currenttag isEqualToString:@"firstName"] && dict) {
        [dict setObject:string forKey:@"firstName"];

    }
    if ([_currenttag isEqualToString:@"lastName"] && dict) {
        [dict setObject:string forKey:@"lastName"];
    }
    if ([_currenttag isEqualToString:@"age"] && dict) {
        [dict setObject:string forKey:@"age"];
    }
    
    NSLog(@"found characters");
}

不斷循環這樣的過程，最後我們就可以解析出整個XML文檔。

另外說一句，這只是解析一般的文檔，如果你跟我曾經一樣學會這個就去解析豆瓣API的XML文檔，會發現行不通。這時因為許多網站因為它的數據較多，為了避免標簽的重復，使用了命名空間，帶有命名空間的XML文檔解析和這稍有不同。

上一頁:IOS 通過button獲取cell
下一頁:ios技術面試題

IOS技巧綜合

iPhone5s換屏多少錢蘋果iPhone5s換屏價格多少？最近有朋友的iPhone5s手機，由於不小心從高地摔落，導致

iphone6/Plus home鍵如何重置？蘋果iphone6/Plus重置home鍵方法圖解 iphone6/Plus home鍵如何重置？蘋果手機的H

iPhone6彎了怎麼辦？iPhone6彎了修多少錢？ iPhone6彎了怎麼辦？iPhone6彎了修多少錢？下面

IOS使用技巧

IOS7技巧 IOS8技巧 IOS9技巧 IOS10技巧 IOS技巧綜合 IOS6技巧蘋果技巧知識錯誤代碼解答

iPhone反應慢怎麼辦？iPhone用起來越來越慢9個提速技巧