YAJL (Objective-C Wrapper)

YAJL.framework is an Objective-C wrapper around the YAJL SAX-style JSON parser.

Download

Mac OS X

YAJL-0.2.6.zip YAJL.framework (2009/10/07)

iPhone

libYAJLIPhone-0.2.6.zip Static Library for iPhone OS 3.0 Simulator & Device (2009/10/07)

Install (Mac OS X)

There are two options. You can install it globally in /Library/Frameworks or with a little extra effort embed it with your project.

Installing in /Library/Frameworks

• Copy YAJL.framework to /Library/Frameworks/
• In the target Info window, General tab:
  • Add a linked library, under Mac OS X 10.5 SDK section, select YAJL.framework

Installing in your project

• Copy YAJL.framework to your project directory (maybe in MyProject/Frameworks/.)
• Add the YAJL.framekwork files (from MyProject/Frameworks/) to your target. It should be visible as a Linked Framework in the target.
• Under Build Settings, add @loader_path/../Frameworks to Runpath Search Paths
• Add New Build Phase | New Copy Files Build Phase.
  • Change the Destination to Frameworks.
  • Drag YAJL.framework into the the build phase
  • Make sure the copy phase appears before any Run Script phases

Install (iPhone)

• Add files (from static library build) to project.
• Under 'Other Linker Flags' in the Test target, add -ObjC and -all_load (So NSObject+YAJL category is loaded).

Usage

To parse JSON from an NSString or NSData:

#import "NSObject+YAJL.h"

NSData *JSONData = [NSData dataWithContentsOfFile:@"example.json"];
NSArray *arrayFromData = [JSONData yajl_JSON];

NSString *JSONString = @"[\"Test\"]";
NSArray *arrayFromString = [JSONString yajl_JSON];

// With options and out error
NSError *error = nil;
NSArray *arrayFromString = [JSONString yajl_JSONWithOptions:YAJLParserOptionsAllowComments error:&error];

To generate JSON from an object:

#import "NSObject+YAJL.h"

NSDictionary *dict = [NSDictionary dictionaryWithObject:@"value" forKey:@"key"];
NSString *JSONString = [dict yajl_JSONString];

// Beautified with custon indent string
NSArray *array = [NSArray arrayWithObjects:@"value1", @"value2", nil];
NSString *JSONString = [dict yajl_JSONStringWithOptions:YAJLGenOptionsBeautify indentString:@"    "];

To use the streaming (or SAX style) parser, use YAJLParser.

NSData *data = [NSData dataWithContentsOfFile:@"example.json"];

YAJLParser *parser = [[YAJLParser alloc] initWithParserOptions:YAJLParserOptionsAllowComments];
parser.delegate = self;
[parser parse:data];
if (parser.parserError) {
    NSLog(@"Error:\n%@", parser.parserError);
}

parser.delegate = nil;
[parser release];

// Include delegate methods from YAJLParserDelegate
/*
- (void)parserDidStartDictionary:(YAJLParser *)parser;
- (void)parserDidEndDictionary:(YAJLParser *)parser;

- (void)parserDidStartArray:(YAJLParser *)parser;
- (void)parserDidEndArray:(YAJLParser *)parser;

- (void)parser:(YAJLParser *)parser didMapKey:(NSString *)key;
- (void)parser:(YAJLParser *)parser didAdd:(id)value;
*/

Streaming Example

YAJLParser *parser = [[[YAJLParser alloc] initWithParserOptions:0] autorelease];
parser.delegate = self;

// A chunk of data comes...
YAJLParserStatus status = [parser parse:chunk1];
// 'status' should be YAJLParserStatusInsufficientData, if its not finished
if (parser.parserError) ...;

// Another chunk of data comes...
YAJLParserStatus status = [parser parse:chunk2];
// 'status' should be YAJLParserStatusOK if its finished
if (parser.parserError) ...;

Usage (Document-style)

To use the document style, use YAJLDocument. Usage should be very similar to NSXMLDocument.

NSData *data = [NSData dataWithContentsOfFile:@"example.json"];
NSError *error = nil;
YAJLDocument *document = [[YAJLDocument alloc] initWithData:data parserOptions:0 error:&error];
// Access root element at document.root
NSLog(@"Root: %@", document.root);
[document release];

Or stream to the document:

YAJLDocument *document = [[YAJLDocument alloc] initWithWithParserOptions:YAJLParserOptionsNone];

NSError *error = nil;
[document parse:chunk1 error:error];
[document parse:chunk2 error:error];

// Access root element at document.root
NSLog(@"Root: %@", document.root);
[document release];