(Objective-C) JSON Paths

Demonstrates using "Chilkat JSON Paths" to access parts of a JSON document, or to iterate over parts.

This example uses the following JSON document:

{
    "nestedArray" : [
			[
				[1,2,3],
				[4,5,6],
				[7,8,9,10]
			],
			[
				[11,12,13],
				[14,15,16],
				[17,18,19,20]
			],
			[
				[21,22,23],
				[24,25,26],
				[27,28,29,30],
				[31,32,33,34,35,36]
			]
		],

	"nestedObject" : {
		"aaa" : {
			"bb1" : {
				"cc1" : "c1Value",
				"cc2" : "c2Value",
				"cc3" : "c3Value"
			},
			"bb2" : {
				"dd1" : "d1Value",
				"dd2" : "d2Value",
				"dd3" : "d3Value"
			}
		}
	},

	"mixture" : {
		"arrayA" : [  
			{ "fruit": "apple", "animal": "horse", "job": "fireman", "colors": ["red","blue","green"] },
			{ "fruit": "pear", "animal": "plankton", "job": "waiter", "colors": ["yellow","orange","purple"] },
			{ "fruit": "kiwi", "animal": "echidna", "job": "astronaut", "colors": ["magenta","tan","pink"] }
			]
	},


        "name.with.dots" : { "grain" : "oats" }

	
}

Chilkat Objective-C Library Downloads MAC OS X (Cocoa) Libs iOS Libs

#import <CkoJsonObject.h>
#import <CkoJsonArray.h>

CkoJsonObject *json = [[CkoJsonObject alloc] init];
json.EmitCompact = NO;

// Assume the file contains the data as shown above..
BOOL success = [json LoadFile: @"qa_data/json/pathSample.json"];
if (success != YES) {
    NSLog(@"%@",json.LastErrorText);
    return;
}

// First, let's get the value of "cc1"
// The path to this value is: nestedObject.aaa.bb1.cc1
NSLog(@"%@",[json StringOf: @"nestedObject.aaa.bb1.cc1"]);

// Now let's get number 18 from the nestedArray.
// It is located at nestedArray[1][2][1]
// (remember: Indexing is 0-based)
NSLog(@"%@%d",@"This should be 18: ",[[json IntOf: @"nestedArray[1][2][1]"] intValue]);

// We can do the same thing in a more roundabout way using the 
// I, J, and K properties.  (The I,J,K properties will be convenient
// for iterating over arrays, as we'll see later.)
json.I = [NSNumber numberWithInt:1];
json.J = [NSNumber numberWithInt:2];
json.K = [NSNumber numberWithInt:1];
NSLog(@"%@%d",@"This should be 18: ",[[json IntOf: @"nestedArray[i][j][k]"] intValue]);

// Let's iterate over the array containing the numbers 17, 18, 19, 20.
// First, use the SizeOfArray method to get the array size:
int sz = [[json SizeOfArray: @"nestedArray[1][2]"] intValue];
// The size should be 4.
NSLog(@"%@%d%@",@"size of array = ",sz,@" (should equal 4)");

// Now iterate...
int i;
for (i = 0; i <= sz - 1; i++) {
    json.I = [NSNumber numberWithInt: i];
    NSLog(@"%d",[[json IntOf: @"nestedArray[1][2][i]"] intValue]);
}

// Let's use a triple-nested loop to iterate over the nestedArray:
int j;
int k;

// szI should equal 1.
int szI = [[json SizeOfArray: @"nestedArray"] intValue];
for (i = 0; i <= szI - 1; i++) {
    json.I = [NSNumber numberWithInt: i];

    int szJ = [[json SizeOfArray: @"nestedArray[i]"] intValue];
    for (j = 0; j <= szJ - 1; j++) {
        json.J = [NSNumber numberWithInt: j];

        int szK = [[json SizeOfArray: @"nestedArray[i][j]"] intValue];
        for (k = 0; k <= szK - 1; k++) {
            json.K = [NSNumber numberWithInt: k];

            NSLog(@"%d",[[json IntOf: @"nestedArray[i][j][k]"] intValue]);
        }

    }

}

// Now let's examine how to navigate to JSON objects contained within JSON arrays.
// This line of code gets the value "kiwi" contained within "mixture"
NSLog(@"%@",[json StringOf: @"mixture.arrayA[2].fruit"]);

// This line of code gets the color "yellow"
NSLog(@"%@",[json StringOf: @"mixture.arrayA[1].colors[0]"]);

// Getting an object at a path:
// This gets the 2nd object in "arrayA"
CkoJsonObject *obj2 = [json ObjectOf: @"mixture.arrayA[1]"];
// This object's "animal" should be "plankton"
NSLog(@"%@",[obj2 StringOf: @"animal"]);

// Note that paths are relative to the object, not the absolute root of the JSON document.
// Starting from obj2, "purple" is at "colors[2]"
NSLog(@"%@",[obj2 StringOf: @"colors[2]"]);

// Getting an array at a path:
// This gets the array containing the colors red, green, blue:
CkoJsonArray *arr1 = [json ArrayOf: @"mixture.arrayA[0].colors"];
int szArr1 = [arr1.Size intValue];
for (i = 0; i <= szArr1 - 1; i++) {
    NSLog(@"%d%@%@",i,@": ",[arr1 StringAt: [NSNumber numberWithInt: i]]);
}

// The Chilkat JSON path uses ".", "[", and "]" chars for separators.  When a name
// contains one of these chars, use double-quotes in the path:
NSLog(@"%@",[json StringOf: @"\"name.with.dots\".grain"]);