I developed this class to download a JSON from a server, parse the result and call a delegate back on the class that called it. Since I am self started I want to know if this is a good practise.
DataController.h
#import <Foundation/Foundation.h>
#import "Reachability.h"
#import "Movie.h"
//This class is a data controller which means that all requests on webservices should be here. We user enum to identify which request is calling this controller
typedef enum {SearchMode}RequestMode;
RequestMode currentMode;
//================
@protocol DataControllerDelegate <NSObject>
@required
- (void)DataControllerRequestSuccessful:(RequestMode)mode;
- (void)DataControllerRequestFailedWithReason:(NSString*)reason;
@end
//=================
@interface DataController : NSObject <NSURLConnectionDataDelegate>{
NSURLConnection *conn;
NSArray *responseArray;
NSMutableData *responseData;
}
@property (nonatomic, assign) id <DataControllerDelegate> delegate;
@property(nonatomic,copy)NSMutableArray *movieArray;
-(id)initAndSearchForMovieWithTitle:(NSString*)title andDelegate:(id <DataControllerDelegate>)del;
@end
DataController.m
//We use MACRO to keep the URL. In the future when we will have more than 1 request we can change the URL for all requests from here.
#define API_URL @"http://api.nytimes.com"
//We do the same for API Key
#define API_KEY @"XXXXXXXXXXXXXXXXXX"
#import "DataController.h"
@implementation DataController
@synthesize delegate,movieArray;
#pragma mark - Init Function
-(id)initAndSearchForMovieWithTitle:(NSString*)title andDelegate:(id<DataControllerDelegate>)del{
self = [super init];
if (self) {
currentMode=SearchMode;
self.delegate=del;
//Check for internet connection
bool internet = [self internetConnectivity];
//Sending the requests on the server
if(internet){
NSString* url = [NSString stringWithFormat:@"%@/svc/movies/v2/reviews/search.json?query=%@&thousand-best=Y&api-key=%@&order=by-title",API_URL,title,API_KEY];
NSLog(@"url%@",url);
NSLog(@"url %@",url);
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:url]];
conn = [[NSURLConnection alloc] initWithRequest:request delegate:self];
[conn start];
}
else
{
//No internet connection
[delegate DataControllerRequestFailedWithReason:@"There is no internet connection available!"];
}
}
return self;
}
#pragma mark - Delegates for NSURLConnection
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
// A response has been received, this is where we initialize the instance var you created
// so that we can append data to it in the didReceiveData method
// Furthermore, this method is called each time there is a redirect so reinitializing it
// also serves to clear it
responseData = [[NSMutableData alloc] init];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
// Append the new data to the instance variable you declared
[responseData appendData:data];
NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
//In some cases the API returns this error
if ([responseString isEqualToString:@"Internal Server Error"]) {
[connection cancel];
[delegate DataControllerRequestFailedWithReason:@"Something went wrong. Please try again!"];
}
}
- (NSCachedURLResponse *)connection:(NSURLConnection *)connection
willCacheResponse:(NSCachedURLResponse*)cachedResponse {
return nil;
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
[connection cancel];
//Request has finished successfuly
[self parseJSONFor:currentMode];
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
[delegate DataControllerRequestFailedWithReason:@"Something went wrong. Please try again!"];
}
#pragma mark - Parse method
-(void)parseJSONFor:(RequestMode)mode{
//Declaring NSError to catch any error on Serialization
NSError *jsonParsingError = nil;
//Init the dictionaries that will help us to retrieve the data from JSON
NSDictionary *movieDictionary = [[NSDictionary alloc]init];
NSDictionary *allDataDictionary = [[NSDictionary alloc]init];
NSDictionary *linkDataDictionary = [[NSDictionary alloc]init];
//Init the arrays that will help us to retrieve data
responseArray = [[NSArray alloc]init];
movieArray = [[NSMutableArray alloc]init];
//In this case the Switch is useless but in the future when we have more request it will help us to diferentiate the parsing for each request.
switch (currentMode) {
case SearchMode:{
//Converting the JSON data to a Dictionary
allDataDictionary = [NSJSONSerialization JSONObjectWithData:responseData options:0 error:&jsonParsingError];
if (jsonParsingError) {
//In case the JSON is invalid we call the failed delegate
[delegate DataControllerRequestFailedWithReason:@"Something went wrong. Please try again!"];
break;
}
//Converting the "Result" object to an array so we can iterate and get all the values
responseArray = [allDataDictionary objectForKey:@"results"];
//Looping through the array and creating the objects Movie and adding them on a new array that will hold the objects
for(int i=0;i<responseArray.count;i++){
Movie *mov = [[Movie alloc]init];
movieDictionary =(NSDictionary*)[responseArray objectAtIndex:i];
//For each string we check that there is no NSNull value because it will crash the app.
//For the reviewer we also make sure that the first letter of its name and surname is capitalized(because sometimes the server returns all chars capital which is inconsistend-ungly
mov.reviewer=[[self validateString:[movieDictionary objectForKey:@"byline"]] capitalizedString];
mov.review=[self validateString:[movieDictionary objectForKey:@"capsule_review"]];
mov.releaseDate=[self validateString:[movieDictionary objectForKey:@"dvd_release_date"]];
mov.title=[self validateString:[movieDictionary objectForKey:@"display_title"]];
mov.movieID=[self validateString:[movieDictionary objectForKey:@"nyt_movie_id"]];
linkDataDictionary= (NSDictionary*)[movieDictionary objectForKey:@"link"];
mov.reviewURL = [linkDataDictionary objectForKey:@"url"];
[movieArray addObject:mov];
}
//Notyfing the ViewController that the request was successfull and the data are ready
[delegate DataControllerRequestSuccessful:SearchMode];
}
break;
default:
break;
}
}
#pragma mark - JSON Helper method
//Checks if the JSON has any NSNull values and convert to N/A string
-(NSString*)validateString:(NSString*)str{
NSString *validatedString;
if (str==(NSString *)[NSNull null]) {
validatedString=@"N/A";
}
else{
validatedString = str;
}
return validatedString;
}
#pragma mark - Internet Connectivity method
//Check the internet connectivity
-(BOOL)internetConnectivity{
Reachability *networkReachability = [Reachability reachabilityForInternetConnection];
NetworkStatus networkStatus = [networkReachability currentReachabilityStatus];
if (networkStatus == NotReachable) {
return FALSE;
}
else
{
return TRUE;
}
}
@end
