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