Quick parser

gistfile1.m

//
//  MSJSonParser.m
//  MySeeen
//
//  Created by Thomas Ricouard on 11/02/12.
//  Copyright (c) 2012 __MyCompanyName__. All rights reserved.
//

#import "MSJSonParser.h"

@implementation MSJSonParser
@synthesize delegate; 


-(id)initWithURL:(NSURL *)URL cacheFileName:(NSString *)filename
{
    self = [super init];
    if (self) {
        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        NSString *documentsDirectory = [paths objectAtIndex:0];
        _filename = [documentsDirectory stringByAppendingPathComponent:filename];
        _URL = URL; 
    }
    return self; 
}
-(void)parseFromServer{
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:_URL
                                                                cachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData 
                                                            timeoutInterval:60];
    _urlConnection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
    if (_urlConnection) {
        _asyncData = [[NSMutableData alloc] init];
    }
    
}

#pragma mark - NSURLConnection delegate
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
	[_asyncData setLength:0];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
	[_asyncData appendData:data];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
	
	NSLog(@"%@", error); 
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
	
    [self connectionDoneSoParse]; 
    
}

#pragma mark - METHOD
-(BOOL)isExistingFile
{
    NSFileManager *fileM = [NSFileManager defaultManager]; 
    return [fileM fileExistsAtPath:_filename]; 
}

-(void)lazyParsingFromFileThenServer
{
    if ([self isExistingFile]){    
        [self parseJsonFromFile]; 
    }
    [self parseFromServer]; 
}

-(void)connectionDoneSoParse
{
    NSJSONSerialization *json = [NSJSONSerialization JSONObjectWithData:_asyncData options:NSJSONReadingAllowFragments error:nil];
    NSDictionary *dic = (NSDictionary *)json; 
    if ([dic objectForKey:@"errors"]) {
        NSArray *errors = [dic objectForKey:@"errors"];
        MSJSonError *error = [[MSJSonError alloc]initWithDictionnary:[errors objectAtIndex:0]]; 
        [delegate jsonParserDidFinishParsingWithError:error]; 
    }
    else{
        [delegate jsonParserDidFinishParsing:dic]; 
        [self writeJsonToFile:json];    
    }
}

-(void)parseJsonFromFile
{
    NSInputStream *input = [NSInputStream inputStreamWithFileAtPath:_filename]; 
    [input open]; 
    NSJSONSerialization *read = [NSJSONSerialization JSONObjectWithStream:input options:NSJSONReadingAllowFragments error:nil]; 
    NSDictionary *dic = (NSDictionary *)read; 
    [delegate jsonParserDidFinishParsing:dic]; 
    [input close]; 
}

-(void)writeJsonToFile:(NSJSONSerialization *)json
{

    NSOutputStream *opt = [NSOutputStream outputStreamToFileAtPath:_filename append:NO];
    [opt open]; 
    [NSJSONSerialization writeJSONObject:json toStream:opt options:NSJSONReadingAllowFragments error:nil];
    [opt close];
}


@end