ios网络学习------8 xml格式数据的请求处理 用代码块封装

#pragma mark 载入xml
- (void)loadXML
{
//获取网络数据。
NSLog(@"load xml");
//从webserver载入数据
NSString *str = @"http://www.baidu.com?format=xml";  //这里是乱写的
//1简历NSURL
NSURL *url = [NSURL URLWithString:str];
//2建立NSURLRequest
NSURLRequest *request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:2.0f];
//3建立NSURLConnect的同步方法载入数据
NSURLResponse *response = nil;
NSError *error = nil;

//同步载入数据
NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
MyXMLParser *myParser = [[MyXMLParser alloc]init];

//懒载入实例化数据
if (self.dataList == nil) {
self.dataList = [NSMutableArray array];
}else{
[self.dataList removeAllObjects];
}

//解析数据
[myParser xmlParserWithData:data StartName:@"video"
startElement:^( NSDictionary *dict) {
//1 实例化currentvideo
self.currentVideo = [[Video alloc]init];
//2 设置videoid
self.currentVideo.videoId = [dict[@"videoId"]integerValue];
} endElement:^(NSString *elementName, NSString *result) {
if ([elementName isEqualToString:@"name"]) {
self.currentVideo.name = result;
}else if ([elementName isEqualToString:@"length"]){
self.currentVideo.length = [result integerValue];
}else if ([elementName isEqualToString:@"videoURL"]){
self.currentVideo.videoId = [result integerValue];
}else if ([elementName isEqualToString:@"imageURL"]){
self.currentVideo.imageURL = result;
}else if ([elementName isEqualToString:@"desc"]){
self.currentVideo.desc = result;
}else if ([elementName isEqualToString:@"teacher"]){
self.currentVideo.teacher = result;
}else if ([elementName isEqualToString:@"video"]){
[self.dataList addObject:self.currentVideo];
}
} finishedParser:^{
self.currentVideo = nil;
[self.tableView reloadData];   //刷新表格数据
} errorParser:^{
NSLog(@"解析出现错误");
//清空暂时数据
self.currentVideo = nil;
//清空数组
[self.dataList removeAllObjects];
}];
}

<pre name="code" class="objc">#import <Foundation/Foundation.h>//代理方法中须要与调用者交互的方法：// 2 交互元素： elementname  attributeDict// 4 交互的元素： elementname 中转的字符串//5 仅通知就可以//6 仅通知就可以//定义块代码：typedef void(^startElementBlock)(NSDictionary *dict);typedef void(^endElementBlock)(NSString *elementName, NSString *result);typedef void(^xmlParserNotificationBlock)();@interface MyXMLParser : NSObject//定义解析方法/*data  xml数据startname 開始的节点名称startElement 開始节点方法endElement  结束节点方法finishedparser 文档解析结束。errorParse  文档解析出错。*/-(void)xmlParserWithData:(NSData *)dataStartName:(NSString *)startNamestartElement:(startElementBlock)startElementendElement:(endElementBlock)endElementfinishedParser:(xmlParserNotificationBlock)finishedParsererrorParser:(xmlParserNotificationBlock)errorParser;@end

<pre name="code" class="objc">#import "MyXMLParser.h"@interface MyXMLParser() <NSXMLParserDelegate>{//记录块代码的成员变量startElementBlock _startElementBlock;endElementBlock _endElementBlock;xmlParserNotificationBlock _finishedBlock;xmlParserNotificationBlock _errorBlock;}//開始节点名称，列如：video  假设检測到此名称， 须要实例化对象@property (strong, nonatomic)NSString *startElementName;//中转字符串@property (strong, nonatomic) NSMutableString *elementString;@end@implementation MyXMLParser//在这种方法里面实现xml的解析。/*data  xml数据startname 開始的节点名称startElement 開始节点方法endElement  结束节点方法finishedparser 文档解析结束。errorParse  文档解析出错。*/- (void)xmlParserWithData:(NSData *)dataStartName:(NSString *)startNamestartElement:(startElementBlock)startElementendElement:(endElementBlock)endElementfinishedParser:(xmlParserNotificationBlock)finishedParsererrorParser:(xmlParserNotificationBlock)errorParser{self.startElementName = startName;//记录块代码_startElementBlock = startElement;_endElementBlock = endElement;_finishedBlock = finishedParser;_errorBlock = errorParser;//定义解析器而且開始解析NSXMLParser *parser = [[NSXMLParser alloc]initWithData:data];[parser setDelegate:self]; //设置代理//開始解析[parser parse]; //这种方法会调用以下的几个方法来实现。}#pragma mark - XML解析器代理方法//所谓须要与外界交互，表示须要与调用发打交道，通知调用放运行某些操作。//1開始解析文档，初始化数据，也不须要与外部交互。- (void)parserDidStartDocument:(NSXMLParser *)parser{//实例化中装字符串if (self.elementString == nil) {self.elementString = [NSMutableString string];}}//2開始解析元素（元素的头部video, 须要实例化对象， attributedict须要设置属性）//须要与外部交互//交互的元素： elementName  attributeDict- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict{if ([elementName isEqualToString:self.startElementName]) {//開始部分代码_startElementBlock(attributeDict);}//開始循环运行第三个方法前，清空中转字符串[self.elementString setString:@""];}//3发现元素字符串（拼接字符串，不须要和外部交互）- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string{[self.elementString appendString:string];}//4结束元素解析，依据elementname和第三步的拼接内容，确定对象属性，须要与外部交互//交互的元素： elementname  中转的字符串- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName{NSString *result = [NSString stringWithString:self.elementString];_endElementBlock(elementName, result);}//5解析文档结束，通常须要调用放刷新数据。//交互的元素： 仅通知就可以- (void)parserDidEndDocument:(NSXMLParser *)parser{[self.elementString setString:@""];_finishedBlock();}//解析出错，通知调用方解析出错(须要与外界交互)。//交互的元素： 仅通知就可以。- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError{NSLog(@"解析出错");[self.elementString setString:@""];//带一个nserror回去会更好。_errorBlock();}@end