Error when get object from array element property - objective-c

Question

I have simple Cocoa application, that parse JSON and pack information of JSON to object of Day class.
Day.h.
#import <Foundation/Foundation.h>
#interface Day : NSObject
#property(retain, nonatomic) NSString *dateString;
#end
main.m
import <Foundation/Foundation.h>
import </Users/Admin/Documents/SimpleJsonParser/SBJSON.h>
#import "Day.h"
int main(int argc, const char * argv[])
{
#autoreleasepool {
// source json object
NSString *jsonSource = #"{\"days\":[{\"dateString\":\"10 december\"},{\"dateString\":\"11 december\"}]}";
SBJsonParser *jsonParser = [[SBJsonParser alloc] init];
NSError *error = nil;
NSDictionary *jsonObjects = [jsonParser objectWithString:jsonSource error:&error];
if(error != nil){
NSLog([error description]);
}
// array of days objects
NSArray *days = [jsonObjects objectForKey:#"days"];
// create empty array
NSMutableArray *daysSource = [[NSMutableArray array] retain];
for(int i = 0; i < [days count]; i++){
NSDictionary *day = [days objectAtIndex:i];
// get dateString
NSString *dateString = [day objectForKey:#"dateString"];
// create Day object
Day* dayObject = [[Day alloc] init];
dayObject.dateString = dateString;
NSLog(dayObject.dateString);
[daysSource addObject:day];
}
NSUInteger temp = [daysSource count];
NSLog(#"Temp is %lu", temp);
Day *myDay = [daysSource objectAtIndex:0];
NSString *dateStringTemp = myDay.dateString;
}
}
And when I run this code, I get this error:
2012-12-11 14:09:50.867 SimpleJsonParser[577:303] -[__NSDictionaryM dateString]: unrecognized selector sent to instance 0x10010e4d0
2012-12-11 14:09:50.869 SimpleJsonParser[577:303] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSDictionaryM dateString]: unrecognized selector sent to instance 0x10010e4d0'
*** First throw call stack:
(
0 CoreFoundation 0x00007fff90a2e0a6 __exceptionPreprocess + 198
1 libobjc.A.dylib 0x00007fff8c6713f0 objc_exception_throw + 43
2 CoreFoundation 0x00007fff90ac46ea -[NSObject(NSObject) doesNotRecognizeSelector:] + 186
3 CoreFoundation 0x00007fff90a1c5ce ___forwarding___ + 414
4 CoreFoundation 0x00007fff90a1c3b8 _CF_forwarding_prep_0 + 232
5 SimpleJsonParser 0x0000000100001700 main + 704
6 libdyld.dylib 0x00007fff850b57e1 start + 0
7 ??? 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminate called throwing an exception
(lldb)
Why property "dateString" of Day class saved as NSDictionary?

Answer 1

You are adding the dictionary object to array not Day object.
Change:
[daysSource addObject:day];
to
[daysSource addObject:dayObject];

Answer 2

The object returned from [daysSource objectAtIndex:0] is an NSDictionary
NSDictionary *myDay = [daysSource objectAtIndex:0];
NSString *dateStringTemp = [myDay objectForKey:#"dateString"];

Answer 3

day is a dictionary. You store it in daySource and then do Day *myDay = [daysSource objectAtIndex:0];