iOS elearning------8 request processing of XML format data in code block encapsulation

#pragma mark load xml-(void) loadxml{//Get network data.    NSLog (@ "load xml");  Load data from the Web server nsstring *str = @ "Http://www.baidu.com?format=xml";    Here is the Scribble//1 cv nsurl nsurl *url = [Nsurl urlwithstring:str]; 2 Establish nsurlrequest nsurlrequest *request = [Nsurlrequest requestwithurl:url cachepolicy:    Nsurlrequestuseprotocolcachepolicy timeoutinterval:2.0f];    3 Establish Nsurlconnect synchronization method to load data nsurlresponse *response = nil;            Nserror *error = nil; Synchronous load Data NSData *data = [nsurlconnection sendsynchronousrequest:request returningresponse:&response error:&    ERROR];        Myxmlparser *myparser = [[Myxmlparser alloc]init];    Lazy Loading instantiated data if (self.datalist = = nil) {self.datalist = [Nsmutablearray array];    }else{[Self.datalist removeallobjects]; }//Parse data [Myparser xmlparserwithdata:data startname:@ "video" startelement:^ (        Nsdictionary *dict) {//1 instantiation Currentvideo self.currentvideo = [[Video alloc]init];  2 Setting VideoID      Self.currentVideo.videoId = [dict[@ "VideoID"]integervalue]; } endelement:^ (NSString *elementname, NSString *result) {if ([elementname isequaltostring:@ "name"]) {s        Elf.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]; //Refresh table Data} errorparser:^{NSLog (@ "Parse error");        Emptying temporary data Self.currentvideo = nil;    Empty array [self.datalist removeallobjects]; }];}

<pre name= "code" class= "OBJC" > #import <foundation/foundation.h>//Proxy methods need to interact with callers://2 interactive elements: elementname  attributedict//4 interactive elements: elementname brokered strings//5 notifications only  //6 only//define block code: typedef void (^startelementblock) ( Nsdictionary *dict); typedef void (^endelementblock) (NSString *elementname, NSString *result); typedef void (^ Xmlparsernotificationblock) (); @interface myxmlparser:nsobject//Definition parsing method/*  node name starting with the data XML startname Startelement Start Node method endElement  End Node method finishedparser document parsing ends. Errorparse  Document parsing error. */-(void) Xmlparserwithdata: (NSData *) Data                 startname: (NSString *) StartName                 startelement: ( Startelementblock) startelement                 endElement: (endelementblock) endElement                 finishedparser: ( Xmlparsernotificationblock) Finishedparser                 errorparser: (xmlparsernotificationblock) ErrorParser; @end

<pre name= "code" class= "OBJC" > #import "MyXMLParser.h" @interface myxmlparser () <nsxmlparserdelegate>{//    The member variable of the record block code Startelementblock _startelementblock;    Endelementblock _endelementblock;    Xmlparsernotificationblock _finishedblock; Xmlparsernotificationblock _errorblock;} Start node name, column such as: Video If this name is detected, you need to instantiate the object @property (strong, nonatomic) nsstring *startelementname;//relay string @property (Strong, nonatomic) nsmutablestring *elementstring, @end @implementation myxmlparser//implement XML parsing in this method. /* Data XML startname start node name startelement start nodes Method endElement End Node method finishedparser document parsing ends. Errorparse document parsing error. */-(void) Xmlparserwithdata: (NSData *) data startname: (NSString *) StartName Startelem ENT: (startelementblock) startelement endElement: (endelementblock) endElement FINISHEDP    Arser: (xmlparsernotificationblock) Finishedparser Errorparser: (xmlparsernotificationblock) errorParser{ Self.startelEmentname = StartName;    Record block Code _startelementblock = startelement;    _endelementblock = endElement;    _finishedblock = Finishedparser;        _errorblock = Errorparser;    Define the parser and start parsing nsxmlparser *parser = [[Nsxmlparser alloc]initwithdata:data]; [Parser setdelegate:self]; Set agent//Start parsing [parser parse]; This method can be implemented by invoking the following methods. } #pragma mark-xml Parser proxy method//The so-called need to interact with the outside, indicating the need to work with the call, notification calls to perform certain operations. 1 Start parsing the document, initializing the data, and not needing to interact with the outside. -(void) Parserdidstartdocument: (Nsxmlparser *) parser{//Instancing The string if (self.elementstring = = nil) {Self.elemen    tstring = [nsmutablestring string]; }}//2 begins parsing elements (the element's head video, needs to instantiate the object, Attributedict needs to set the property)//elements that need to interact with//interact with the outside: ElementName attributedict-(void) Parser: ( Nsxmlparser *) Parser didstartelement: (NSString *) elementname NamespaceURI: (NSString *) NamespaceURI QualifiedName: (        NSString *) QName attributes: (nsdictionary *) attributedict{if ([elementname isEqualToString:self.startElementName]) {  Start Part code _startelementblock (attributedict);  }//Before starting the loop to execute the third method, empty the brokered string [self.elementstring setstring:@ "];} 3 found element string (stitching string, no need and external interaction)-(void) Parser: (Nsxmlparser *) parser foundcharacters: (NSString *) string{[ Self.elementstring appendstring:string];} 4 End element parsing, according to ElementName and the stitching content of the third step, determine the object properties, need to interact with the external//Interaction elements: ElementName Relay string-(void) Parser: (Nsxmlparser *) parser    Didendelement: (NSString *) elementname NamespaceURI: (NSString *) NamespaceURI qualifiedname: (NSString *) qName{    NSString *result = [NSString stringWithString:self.elementString]; _endelementblock (elementname, result);} 5 parsing the end of the document, it is usually necessary to call the drop refresh data.    Interactive elements: Notification only-(void) Parserdidenddocument: (Nsxmlparser *) parser{[self.elementstring setstring:@ "]; _finishedblock ();} Parsing error, notifying caller parsing error (requires interaction with outside). Elements of Interaction: notifications only.    -(void) Parser: (Nsxmlparser *) parser parseerroroccurred: (Nserror *) parseerror{NSLog (@ "Parse error");    [Self.elementstring setstring:@ ""];    It would be better to take a nserror back. _errorblock ();} @end