iOS Development-JSON parsing

JSON parsing

What is JSON
JSON is a lightweight data format that is typically used for data interaction
Data returned by the server to the client, usually in JSON format or XML format (except for file downloads)

The format of JSON is much like the dictionary and array in OC

{"name"jack", "age10}{"names["jack", "rose", "jim"]}

Note points in the standard JSON format: key must be double-quoted

To dig out specific data from JSON, you have to parse the JSON
JSON conversion to OC data type

JSON–OC Conversion Table

JSON	OC
Curly braces {}	Nsdictionary
Brackets []	Nsarray
Double quote ""	NSString
Number 10, 10.8	NSNumber

JSON parsing scheme

In iOS, there are 4 common parsing scenarios for JSON
Third-party frameworks: Jsonkit, Sbjson, Touchjson (performance from left to right, worse)
Apple native (comes with): Nsjsonserialization (Best performance)

NSJSONSerialization的常见方法//JSONOC对象+ (id)JSONObjectWithData:(NSData *)data options:(NSJSONReadingOptions)opt error:(NSError **)error;//OCJSON数据 + (NSData *)dataWithJSONObject:(id)obj options:(NSJSONWritingOptions)opt error:(NSError **)error;

Parsing JSON from the server

JSON parsing instance

 @interface viewcontroller ()@property(Weak,nonatomic)IboutletUitextfield *username;@property(Weak,nonatomic)IboutletUitextfield *pwd;-(ibaction) login;@end @implementation viewcontroller - (void) viewdidload{[SuperViewdidload];additional setup after loading the view, typically from a nib.}- (void) Touchesbegan: (Nsset *) touches withevent: (uievent *) event{[ Self. ViewEndediting:YES];} - (ibaction) Login {//1. User name    NSString*usernametext = Self. Username. Text;if(Usernametext. Length==0) {[Mbprogresshud showerror:@"Please enter user name"];return; }//2. Password    NSString*pwdtext = Self. PWD. Text;if(Pwdtext. Length==0) {[Mbprogresshud showerror:@"Please enter your password"];return; }//3. Send the user name and password to the server (take the HTTP protocol)    //Create a URL: request path    NSString*URLSTR = [NSStringstringwithformat:@"http://localhost:8080/server/login?username=%@&pwd=%@", Usernametext, Pwdtext];Nsurl*url = [NsurlURLWITHSTRING:URLSTR];//Create a request    nsurlrequest*request = [nsurlrequestRequestwithurl:url];//NSLog (@ "Begin---");    //Send a sync request (send a request on the main thread)    //queue: Store Completionhandler this taskNsoperationqueue *queue = [Nsoperationqueue mainqueue]; [nsurlconnectionSendasynchronousrequest:request queue:queue Completionhandler: ^ (nsurlresponse *response, NSData *data,Nserror*connectionerror) {//This block will be automatically called when the request is complete        if(Connectionerror | | data = =Nil) {[Mbprogresshud showerror:@"Request Failed"];return; }//Parse the JSON data returned by the server        nsdictionary*dict = [nsjsonserialization jsonobjectwithdata:data options:nsjsonreadingmutableleaves Error:Nil];NSString*error = dict[@"Error"];if(Error) {//{"Error": "User name does not exist"}            //{"Error": "Password is incorrect"}[Mbprogresshud Showerror:error]; }Else{//{"Success": "Login Successful"}            NSString*success = dict[@"Success"];        [Mbprogresshud showsuccess:success]; }     }];//NSLog (@ "End---");}@end

Example of video JSON data parsing

Model class

#import  <foundation/ Foundation.h> @interface  video:nsobject/** * ID */  @property  (nonatomic, assign) int  Id /** * duration */  @property  (Nonatomic, assign) int  length; /** * Picture (VIDEO) */  @property  (nonatomic, copy) NSString *image; /** * Video name */  @property  (nonatomic, copy) NSString *name; /** * Video Playback path */  @property  (nonatomic, copy) NSString *url;+ (Instancetype) videowithdict: (Nsdictionary *) dict;  @end   

#import "Video.h"@implementation Video+ (instancetype)videoWithDict:(NSDictionary *)dict{    Video *video = [[self alloc] init];    [video setValuesForKeysWithDictionary:dict];    return video;}@end

#import <MediaPlayer/MediaPlayer.h> #define URL (path) [Nsurl urlwithstring:[nsstring stringwithformat:@ "http://localhost:8080/server/%@", Path]]  @interface videosviewcontroller ()@property(nonatomic,Strong)Nsmutablearray*videos;@end @implementation videosviewcontroller - (Nsmutablearray*) videos{if(!_videos) { Self. Videos= [[NsmutablearrayALLOC] init]; }return_videos;} - (void) viewdidload{[SuperViewdidload];/** loading server's latest video information * /    //1. Create a URL    Nsurl*url = URL (@"Video");//2. Create a request    nsurlrequest*request = [nsurlrequestRequestwithurl:url];//3. Send Request[nsurlconnectionSendasynchronousrequest:request Queue:[nsoperationqueue Mainqueue] completionhandler:^ (NSURLResponse *response, NSData *data,Nserror*connectionerror) {if(Connectionerror | | data = =Nil) {[Mbprogresshud showerror:@"The Internet is busy, please try again later!" "];return; }//parsing JSON data        nsdictionary*dict = [nsjsonserialization jsonobjectwithdata:data options:nsjsonreadingmutableleaves Error:Nil];Nsarray*videoarray = dict[@"Videos"]; for(nsdictionary*videodict in Videoarray) {Hmvideo *video = [Hmvideo videowithdict:videodict]; [ Self. VideosAddobject:video]; }//Refresh table[ Self. TableViewReloaddata]; }];}#pragma mark-table view data source- (Nsinteger) TableView: (UITableView*) TableView numberofrowsinsection: (Nsinteger) section{return  Self. Videos. Count;} - (UITableViewCell*) TableView: (UITableView*) TableView Cellforrowatindexpath: (Nsindexpath*) indexpath{Static NSString*id = @"Video";UITableViewCell*cell = [TableView dequeuereusablecellwithidentifier:id];if(!cell) {cell = [[UITableViewCellAlloc] Initwithstyle:uitableviewcellstylesubtitle Reuseidentifier:id]; } Hmvideo *video = Self. Videos[Indexpath. Row]; Cell. Textlabel. Text= Video. Name; Cell. Detailtextlabel. Text= [NSStringstringwithformat:@"duration:%d minutes", video. Length];//Show Video    Nsurl*url = Hmurl (video. Image); [Cell. ImageViewSd_setimagewithurl:url placeholderimage:[UIImageimagenamed:@"Placehoder"]];returnCell;}#pragma mark-Proxy method- (void) TableView: (UITableView*) TableView Didselectrowatindexpath: (Nsindexpath*) indexpath{//1. Remove the corresponding video modelHmvideo *video = Self. Videos[Indexpath. Row];//2. Create a video playback controller that comes with your system    Nsurl*url = URL (video. URL); Mpmovieplayerviewcontroller *PLAYERVC = [[Mpmovieplayerviewcontroller alloc] initwithcontenturl:url];//3. Display Player[ SelfPRESENTVIEWCONTROLLER:PLAYERVC Animated:YESCompletion:Nil];}@end

iOS Development-JSON parsing