iOS 中的XML解析代码（SAX）

1、XML解析（SAX）

NSXMLParser SAX 大文件

1）打开文档

- (void)parserDidStartDocument:(NSXMLParser *)parser

2）开始查找起始标签

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

开始元素 : elementName
元素属性 : attributeDict

3）获取标签内容

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

获取内容 : string

4）查找结束标签

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

结束元素 : elementName namespaceURI 和 qName 为空值

5）关闭文档(查询结束)

- (void)parserDidEndDocument:(NSXMLParser *)parser

实现原理：

• 1.在查找起始标签的时候，判断elementName是否与对应的字符串相等，并将接收到的内容删除

• 2.因为获取内容的时候会出现获取两次 则使用追加方法，防止多次执行获取内容的方法 string + @“ "

• 3.在查找结束标签的时候，判断elementName是否与对应的字符串相等，并将获取的模型加载到可变数组中，作为数据源，进行其他操作，再判断是否与对应的字符串不相等，利用kvc将对应的结束标签作为KEY值，对应获取的内容作为value值

//
//  ViewController.m
//
//
//  Created by peng on 16/2/19.
//  Copyright (c) 2016年 pss. All rights reserved.
//

#import "ViewController.h"
#import "PSSTrainInfo.h"

static NSString *identifier = @"cellID";

@interface ViewController ()<UITableViewDataSource, UITableViewDelegate, NSXMLParserDelegate>

@property (nonatomic, strong) UITableView *tableView;

@property (nonatomic, strong) NSMutableArray *dataList;

@property (nonatomic, strong) PSSTrainInfo *model;

@property (nonatomic, strong) NSMutableString *muString;

@end

@implementation ViewController

- (UITableView *)tableView {

    if (!_tableView) {
        _tableView = [[UITableView alloc] initWithFrame:self.view.bounds style:UITableViewStylePlain];

        _tableView.delegate = self;
        _tableView.dataSource = self;

    }
    return _tableView;
}

- (NSMutableString *)muString {

    if (!_muString) {
        _muString = [NSMutableString string];
    }
    return _muString;
}

- (NSMutableArray *)dataList {

    if (!_dataList) {
        _dataList = [NSMutableArray array];
    }
    return _dataList;
}

- (PSSTrainInfo *)model {

    if (!_model) {
        _model = [[PSSTrainInfo alloc] init];
    }
    return _model;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

    return self.dataList.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:identifier];

    if (!cell) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:identifier];
    }

    return cell;
}

- (void)parserDidStartDocument:(NSXMLParser *)parser  {

    NSLog(@"开始解析");

}

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

    NSLog(@"起始元素:%@", elementName);

    if ([elementName isEqualToString:@"trainDetailInfo"]) {

        [self.model setValuesForKeysWithDictionary:attributeDict];

    }
    self.muString = nil;
}

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

    NSLog(@"内容:%@", string);

    [self.muString appendString:string];

}

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

    NSLog(@"结束元素:%@", elementName);

    if ([elementName isEqualToString:@"trainDetailInfo"]) {

        [self.dataList addObject:self.model];

    }else if (![elementName isEqualToString:@"dataSet"] && ![elementName isEqualToString:@"diffgr:diffgram"]) {

        [self.model setValue:self.muString forKey:elementName];

    }

}

- (void)parserDidEndDocument:(NSXMLParser *)parser {

    NSLog(@"结束解析");

    [self.tableView reloadData];

    NSLog(@"%@",self.dataList);

}

- (void)viewDidLoad
{
    [super viewDidLoad];

    NSURL *url = [NSURL URLWithString:@"http://192.168.1.2/train.xml"];

    NSURLRequest *request = [NSURLRequest requestWithURL:url cachePolicy:0 timeoutInterval:15];

    [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {

        NSXMLParser *parser = [[NSXMLParser alloc] initWithData:data];

        parser.delegate = self;

        [parser parse];

    }];

    [self.view addSubview:self.tableView];

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

@end