iphone, SBJsonWriter .. converting an object - xcode

Question

I want to post a json object to a request. But JSONWriter doesn't seem to convert my object, don't know what I'm doing wrong ...
here's my code for the conversion..
customer = [[Customer alloc] init];
Address *tempAddr = [[Address alloc] init];
tempAddr.Line1=strAddr1 ;
tempAddr.Zip =strPost;
tempAddr.City =strStreet;
[customer setInvoiceAddress:tempAddr];
customer.FirstName=strFirstName;
customer.LastName=strLastName;
customer.CellPhone=strCellPhone;
customer.Phone=strPhone;
customer.Email=strEmail;
SBJsonWriter *writer = [SBJsonWriter alloc];
NSString *jsonConvertedObj = [writer stringWithObject:customer];
NSLog(#"the json converted object ... %#", jsonConvertedObj);
Please help. I've no idea what's wrong with the code above.

Answer 1

To figure out why your Json parsing fails, You shoud use this approach:
NSError *error = nil;
NSString * jsonTest = [[[SBJsonWriter alloc] init] stringWithObject:jsonTestDictionary error:&error];
if ( ! jsonTest ) {
NSLog(#"Error: %#", error);
}else{
NSLog(#"%#", jsonTest);
}
Here is a simple code demonstrating how to use it:
#import <Foundation/Foundation.h>
#import "SBJsonWriter.h"
#import "SBJsonParser.h"
int main(int argc, const char * argv[])
{
#autoreleasepool {
NSDictionary* aNestedObject = [NSDictionary dictionaryWithObjectsAndKeys:
#"nestedStringValue", #"aStringInNestedObject",
[NSNumber numberWithInt:1], #"aNumberInNestedObject",
nil];
NSArray * aJSonArray = [[NSArray alloc] initWithObjects: #"arrayItem1", #"arrayItem2", #"arrayItem3", nil];
NSDictionary * jsonTestDictionary = [NSDictionary dictionaryWithObjectsAndKeys:
#"stringValue", #"aString",
[NSNumber numberWithInt:1], #"aNumber",
[NSNumber numberWithFloat:1.2345f], #"aFloat",
[[NSDate date] description], #"aDate",
aNestedObject, #"nestedObject",
aJSonArray, #"aJSonArray",
nil];
// create JSON output from dictionary
NSError *error = nil;
NSString * jsonTest = [[[SBJsonWriter alloc] init] stringWithObject:jsonTestDictionary error:&error];
if ( ! jsonTest ) {
NSLog(#"Error: %#", error);
}else{
NSLog(#"%#", jsonTest);
}
}
return 0;
}
outputs
{
"aDate":"2012-09-12 07:39:00 +0000",
"aFloat":1.2345000505447388,
"nestedObject":{
"aStringInNestedObject":"nestedStringValue",
"aNumberInNestedObject":1
},
"aJSonList":["arrayItem1","arrayItem2","arrayItem3"],
"aString":"stringValue",
"aNumber":1
}
Note:
Using 'error' allowed me to figure out that if you write [NSDate
date] instead of [[NSDate date] description] you will get a "JSON
serialisation not supported for
__NSTaggedDate" error.
notice the float rounding error... 1.2345 became 1.2345000505447388

Answer 2

AFAIK SBJSONWriter only supports conversion of dictionaries and arrays to JSON strings. It won't work for arbitrary objects.
Edit: Here is the corresponding implementation, which returns nil if the supplied object is neither a dictionary nor an array.
- (NSString*)stringWithObject:(id)value {
if ([value isKindOfClass:[NSDictionary class]] || [value isKindOfClass:[NSArray class]]) {
return [self stringWithFragment:value];
}
[self clearErrorTrace];
[self addErrorWithCode:EFRAGMENT description:#"Not valid type for JSON"];
return nil;
}