iOS JSON解析

解析json成dic对象

-(void)fetchedData:(NSData*)responseData {//parse out the json dataNSError* error;
    NSDictionary* json =[NSJSONSerialization 
        JSONObjectWithData:responseData //1
 
        options:kNilOptions 
        error:&error];
 
    NSArray* latestLoans =[json objectForKey:@"loans"]; //2
 
    NSLog(@"loans: %@", latestLoans); //3
}

把对象生成json string
//build an info object and convert to json
NSDictionary* info =[NSDictionary dictionaryWithObjectsAndKeys:[loan objectForKey:@"name"], 
    @"who",
  [(NSDictionary*)[loan objectForKey:@"location"] 
    objectForKey:@"country"], 
    @"where",
  [NSNumber numberWithFloat: outstandingAmount], 
    @"what",
  nil];
 
//convert object to data
NSData* jsonData =[NSJSONSerialization dataWithJSONObject:info 
  options:NSJSONWritingPrettyPrinted error:&error];

//print out the data contents
jsonSummary.text =[[NSString alloc] initWithData:jsonData                                        
  encoding:NSUTF8StringEncoding];

添加json方法至dic
@interfaceNSDictionary(JSONCategories)
+(NSDictionary*)dictionaryWithContentsOfJSONURLString:(NSString*)urlAddress;
-(NSData*)toJSON;
@end
 
@implementationNSDictionary(JSONCategories)
+(NSDictionary*)dictionaryWithContentsOfJSONURLString:(NSString*)urlAddress{
    NSData* data =[NSData dataWithContentsOfURL:[NSURL URLWithString: urlAddress]];
    __autoreleasing NSError* error =nil;
    id result =[NSJSONSerialization JSONObjectWithData:data 
      options:kNilOptions error:&error];
    if(error !=nil)returnnil;
    return result;
}
 
-(NSData*)toJSON{
    NSError* error =nil;
    id result =[NSJSONSerialization dataWithJSONObject:self 
      options:kNilOptions error:&error];
    if(error !=nil)returnnil;
    return result;    
}@end

使用列子
NSDictionary* myInfo =[NSDictionary dictionaryWithContentsOfJSONURLString:@"http://www.yahoo.com/news.json"];
NSDictionary* information =[NSDictionary dictionaryWithObjectsAndKeys:@"orange",@"apple",@"banana",@"fig",nil];
NSData* json =[information toJSON];

判断是否可json化

BOOL isTurnableToJSON =[NSJSONSerialization isValidJSONObject: object]