问题
I'm trying to serialize an objc object with Json to send it to a server.
That same server sends the following on GET for this object type:
{
"TypeProperties":[
{"Key":"prop 0","Value":"blah 0"},
{"Key":"prop 1","Value":"blah 1"},
{"Key":"prop 2","Value":"blah 2"},
{"Key":"prop 3","Value":"blah 3"}
],
"ImageURls":[
{"Key":"url 0","Value":"blah 0"},
{"Key":"url 1","Value":"blah 1"},
{"Key":"url 2","Value":"blah 2"},
{"Key":"url 3","Value":"blah 3"}
]
}
SBJsonWriter produces the following for the matching object/type that I've created in objc:
{
"TypeProperties": {
"key 2": "object 2",
"key 1": "object 1",
"key 4": "object 4",
"key 0": "object 0",
"key 3": "object 3"
},
"ImageUrls": {
"key 0": "url 0",
"key 1": "url 1",
"key 2": "url 2"
}
}
This is how I'm using SBJsonWriter:
SBJsonWriter *writer = [[SBJsonWriter alloc] init];
writer.humanReadable = YES;
NSString* json = [writer stringWithObject:itemToAdd];
Here's my implementation of proxyForJson in the class being serialized (required by SBJsonWriter):
- (NSDictionary*) proxyForJson
{
return [NSMutableDictionary dictionaryWithObjectsAndKeys:
self.typeProperties, @"TypeProperties",
self.imageUrls, @"ImageUrls",
nil];
}
The class being serialized contains only the two properties: typeProperties and imageUrls (both are NSMutableDictionary).
Now, the problem: the server (not surprisingly) does not parse the Json produced by SBJsonWriter when I perform a POST. And the question: how do I produce Json that matches that which is provided by the server (assuming that matching Json would be parsed correctly on upload).
Thanks in advance for any help.
回答1:
In JSON, { }
represents an object (key/value pairs) and [ ]
represents an array. Judging by the sample you provided, here's what your server expects:
Top Object: dictionary with two keys: TypeProperties
and ImageUrls
.
TypeProperties and ImageUrls: each is an array containing one or more objects with two keys: Key
and Value
. Each key should have its respective value.
To comply with what your server expects, you need a structure similar to this (note this is just a bare example, written directly here, but should point you in the right direction):
NSDictionary *object = [NSDictionary dictionaryWithObjectsAndKeys:
@"prop 0", @"Key",
@"blah 0", @"Value",
nil];
NSArray *typeProperties = [NSArray arrayWithObjects:
object, // Add as many similar objects as you want
nil];
NSArray *imageUrls = [NSArray arrayWithObjects:
object, // Add as many similar objects as you want
nil];
Then, in your proxyForJson
method, you can use:
- (NSDictionary*) proxyForJson
{
return [NSDictionary dictionaryWithObjectsAndKeys:
typeProperties, @"TypeProperties",
imageUrls, @"ImageUrls",
nil];
}
回答2:
Here is a simple code demonstrating how to use SBJsonWriter:
#import <Foundation/Foundation.h>
#import "SBJsonWriter.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
}
Notes:
- 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
来源:https://stackoverflow.com/questions/11765037/sbjsonwriter-nested-nsdictionary