Request processing for iOS elearning------6 JSON Format data

#import "MainViewController.h" #import "Video.h" #define Kbaseurl @ "Http://192.168.3.252/~apple" @interface Mainviewcontroller () <uitableviewdatasource, uitableviewdelegate> @property (Strong, nonatomic) NSArray * DataList, @property (weak, nonatomic) UITableView *tableview; @end @implementation Mainviewcontroller

</pre><p class= "P1" >/*</p><p class= "P2" ><span class= "S1" > </span> In the development of network application, </p><p class= "P2" ><span class= "S1" > 1 </span> data is synchronously loaded, can guarantee the user to see </p> <p class= "P2" ><span class= "S1" > 2 </span> image, audio, video is loaded asynchronously. Can ensure that the main thread without blocking the use of the premise, users can gradually see the multimedia information. </p><p class= "P1" > */</p><pre code_snippet_id= "412158" Snippet_file_name= "blog_20140630 _1_3481337 "name=" code "class=" OBJC "> #pragma mark materialized View-(void) loadview{self.view = [[UIView alloc]initwithframe:[u    Iscreen Mainscreen].applicationframe];    1 TableView cgrect frame = self.view.bounds; UITableView *tableview = [[UITableView alloc]initwithframe:cgrectmake (0, 0, frame.size.width, frame.size.height-44)    Style:uitableviewstyleplain];    1) data source [TableView setdatasource:self];    2) Agent [TableView setdelegate:self];    ) Set table height [TableView setrowheight:80];    [Self.view Addsubview:tableview]; Self.tableview = tAbleview;    ToolBar Uitoolbar *toolbar = [[Uitoolbar alloc]initwithframe:cgrectmake (0, TableView.bounds.size.height, 320, 44)];        [Self.view Addsubview:toolbar]; Add toolbar button Uibarbuttonitem *item1 = [[Uibarbuttonitem alloc]initwithtitle:@ ' load json ' style:    Uibarbuttonitemstyledone target:self Action: @selector (Loadjson)]; Uibarbuttonitem *item2 = [[Uibarbuttonitem alloc]initwithtitle:@ "Load xml" Style:uibarbuttonitemstyledone target:self    Action: @selector (LoadXML)]; Uibarbuttonitem *item3 = [[Uibarbuttonitem alloc]initwithbarbuttonsystemitem:uibarbuttonsystemitemflexiblespace    Target:nil Action:nil]; [ToolBar setitems:@[item3, Item1, Item3, ITEM2, Item3]];} #pragma the Mark-uitableview data source method is necessary for UITableView the following two methods are required. -(Nsinteger) TableView: (UITableView *) TableView numberofrowsinsection: (nsinteger) section{return Self.dataList.count;} This method is called once for each row that is populated. Know that all the lines on the interface are filled. ,-(UITableViewCell *) TableView: (UITableView *) TableView Cellforrowatindexpath: (Nsindexpath *) Indexpath{//Use the refillable identifier to query for reusable cells static nsstring *id = @ "MyCell";        UITableViewCell *cell = [TableView dequeuereusablecellwithidentifier:id];    if (cell = = nil) {cell = [[UITableViewCell alloc]initwithstyle:uitableviewcellstylesubtitle Reuseidentifier:id];        }//Set cell contents Video *v = Self.datalist[indexpath.row];    Cell.textLabel.text = V.name;    Cell.detailTextLabel.text = V.teacher;    Load picture//1) synchronously load the network picture, the synchronization method for these instructions will not be executed until the command is completed. Note: When developing a network app, do not use the Sync method to load the picture, otherwise it will seriously affect the user experience//nsstring *imagepath = [NSString stringwithformat:@ "%@%@", Kbaseurl, v.imageurl];//Nsurl *imageurl = [Nsurl urlwithstring:imagepath];//nsdata *imagedata = [NSData DataWithContentsOfUR l:imageurl];//UIImage *image = [UIImage imagewithdata:imagedata];//////2] asynchronously Load network Pictures///////////Network connections themselves have asynchronous commands Sendasyn    c//[Cell.imageview Setimage:image];        If the cached image does not exist if (v.cacheimage = = nil) {//Use the default image placeholder, you can guarantee that there is an image and that there is a place. UIImage *image = [UIImage imagenamed:@ "User_Default.png "]; [Cell.imageview Setimage:image];    Use the default image placeholder//To open an asynchronous connection to load the image, since loading is complete, you need to refresh the corresponding table navigation [self loadimageasyncwithindexpath:indexpath];    }else {[Cell.imageview setimage:v.cacheimage];    }//[self Loadimageasyncwithurl:imageurl ImageView:cell.imageView]; return cell;} #pragma mark asynchronously loads the network picture//Because UITableView is reusable, in order to avoid the user to quickly and frequently refresh the table, resulting in data conflicts, can not be directly uiimageview into the asynchronous method// The correct workaround is to pass the indexpath of the table row into the Async method, and after loading the finished image, refresh the specified row directly. -(void) Loadimageasyncwithindexpath: (Nsindexpath *) indexpath{Video *v = Self.datalist[indexpath.row];//Remove the row currently being populated N    sstring *imagepath = [NSString stringwithformat:@ "%@%@", Kbaseurl, V.imageurl];        Nsurl *imageurl = [Nsurl Urlwithstring:imagepath];    NSLog (@ "%@%@", url, ImageView);    1 request Nsurlrequest *request = [Nsurlrequest Requestwithurl:imageurl]; 2 Connection SendAsync asynchronous request [Nsurlconnection sendasynchronousrequest:request Queue:[nsoperationqueue Mainqueue] completionhandler:^ (Nsurlresponse *response, NsdatA *data, Nserror *error) {//uiimage *image = [UIImage imagewithdata:data];        [ImageView Setimage:image];        Saves network data to a cached image.        V.cacheimage = [UIImage imagewithdata:data];    Refresh table [Self.tableview Reloadrowsatindexpaths:@[indexpath] withrowanimation:uitableviewrowanimationleft]; }];}    #pragma mark handles the JSON data-(void) Handlerjsondata: (NSData *) data{the [] representation of a data in a//json file.     Deserialize JSON data/* Serialization: Convert a Nsboject to serial data for transmission over the Internet.     Deserialization: Reverses the data obtained on the network to the object we need. *////The second parameter is a parsing method, generally with nsjsonreadingallowfragments nsarray *array = [nsjsonserialization jsonobjectwithdata:data options        : Nsjsonreadingallowfragments Error:nil];  NSLog (@ "%@", array);        JSON parsing is data in nsarray format.    Tip: If you are developing a network application, you can save the deserialized object to the sandbox for later development.    Nsarray *docs = Nssearchpathfordirectoriesindomains (NSDocumentDirectory, Nsuserdomainmask, YES);    NSString *path = [docs[0]stringbyappendingpathcomponent:@ "Json.plist"]; [Array Writetofile:path atomically:yes]; Put the array insideThe data is written to the jspn.plist in the sandbox.    Assigning a value to a data list nsmutablearray *arraym = [Nsmutablearray array];        For (nsdictionary *dict in array) {video *video = [[Video Alloc]init];        Assign a value to video [video Setvaluesforkeyswithdictionary:dict];    [Arraym Addobject:video];    } self.datalist = Arraym;        Refresh table [Self.tableview Reloaddata];  NSLog (@ "%@", Arraym); This will call the video inside the description and Nsarray+log inside the Descriptionwithlocale} #pragma mark load json-(void) loadjson{NSLog (@ "load    JSON ");  Load data from the Web server nsstring *str = @ "Http://www.baidu.com?format=json";    This is a doodle.//Hint: NSData itself has a synchronous method, but in the actual development, do not use the secondary method//When using the NSData synchronization method, cannot specify the time-out period, if the server connection is not normal, will affect the user experience.    NSData *data = [NSData datawithcontentsofurl:[nsurl urlwithstring:str];    CV nsurl Nsurl *url = [Nsurl urlwithstring:str]; Establish nsurlrequest nsurlrequest *request = [Nsurlrequest requestwithurl:url cachepolicy:    Nsurlrequestuseprotocolcachepolicy timeoutinterval:2.0f]; Build Nsurlconnect synchronization method to load data nsurlrEsponse *response = nil;    Nserror *error = nil; Synchronous load Data NSData *data = [nsurlconnection sendsynchronousrequest:request returningresponse:&response error:&    ERROR];        Error handling if (data! = nil) {//The following two sentences themselves have little meaning and are used only for tracking debugging.        NSString *result = [[NSString alloc]initwithdata:data encoding:nsutf8stringencoding];                NSLog (@ "%@", result);        Do not convert NSData to nsstring while processing network data.    [Self handlerjsondata:data];    }else if (data = = Nil && error = = nil) {NSLog (@ "null data");    }else {NSLog (@ "%@", error.localizeddescription); }} #pragma mark loaded xml-(void) loadxml{NSLog (@ "load xml");} -(void) viewdidload//{//[Super viewdidload];//} @end