How to JSON encode arrays in array from iOS to PHP - ios

Question

I try to JSON encode NSDictionary into NSArray upload to PHP web-services.
This is how I JSON encode my NSArray:
NSError * error;
NSData * jsonData = [NSJSONSerialization dataWithJSONObject:my_array_1 options:0 error:&error];
NSString * jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
jsonString = [jsonString stringByReplacingOccurrencesOfString:#"\"" withString:#"\\\""];
Then I insert this JSON String into another array by:
NSString * jsonRequest = [NSString stringWithFormat: #"{\"request\":\"syncBookmark\",\"bookmark_array\":\"%#\",\"user_id\":\"%#\"}", jsonString, user_id, nil];
NSData * requestData = [NSData dataWithBytes:[jsonRequest UTF8String] length:[jsonRequest length]];
Before I request the webservices, the JSON encoded string is like:
{"request":"syncBookmark","bookmark_array":"[{\"PostId\":\"4\",\"last_edit_date\":\"2014-03-03 01:05:37\",\"BookmarkId\":\"1\",\"last_sync_date\":\"\",\"is_active\":\"1\"}]","user_id":"7"}
I can echo the 'user_id' in PHP which is '7' correctly, but when I check the array - is_array($bookmark_array) in PHP it just return FALSE. Am I doing the way wrongly to put arrays in array?

Answer 1

This is because you enter JSON string as string and it is obviously escaped by the stringWithFormat method.
You should create a NSDictionary and serialize that together. So instead of serializing my_array_1 variable, you will serialize the dictionary.
Create the dictionary:
NSDictionary* dictionary = #{ #"request" : #"syncBookmark", #"bookmark_array" : my_array_1 };
Then serialize the dictionary:
NSError * error;
NSData * jsonData = [NSJSONSerialization dataWithJSONObject:dictionary options:0 error:&error];
NSString * jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
This is the correct way to serialize a JSON object, not inserting serialized objects into another string. Although I see why you wanted to do that.

Answer 2

Don't bother doing the stringByReplacingOccurrencesOfString stuff. Let NSJSONSerialization do all of the necessary quoting for you.
So, if you really need that jsonString as a string that your PHP will recursively un-encode, just JSON encode the array, and then put that in another dictionary and then encode that again:
NSError *error;
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:my_array_1 options:0 error:&error];
NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
NSDictionary *dictionary = #{#"request" : #"syncBookmark",
#"bookmark_array" : jsonString,
#"user_id" : user_id};
NSData *finalData = [NSJSONSerialization dataWithJSONObject:dictionary options:0 error:&error];
That should create a payload much like you said you wanted in your question.
Having said that, a more logical approach would be:
NSError *error;
NSDictionary *dictionary = #{#"request" : #"syncBookmark",
#"bookmark_array" : my_array_1,
#"user_id" : user_id};
NSData *finalData = [NSJSONSerialization dataWithJSONObject:dictionary options:0 error:&error];
If that's what generated your payload, then your PHP wouldn't have to do multiple calls to json_decode.