将字典或者数组转换成JSON数据或者字符串

源码：

NSDictionary+JSON.h 与 NSDictionary+JSON.m

//
//  NSDictionary+JSON.h
//  Category
//
//  Created by YouXianMing on 15-2-09.
//  Copyright (c) 2014年 YouXianMing. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface NSDictionary (JSON)

/**
 *  转换成JSON串字符串（没有可读性）
 *
 *  @return JSON字符串
 */
- (NSString *)toJSONString;

/**
 *  转换成JSON串字符串（有可读性）
 *
 *  @return JSON字符串
 */
- (NSString *)toReadableJSONString;

/**
 *  转换成JSON数据
 *
 *  @return JSON数据
 */
- (NSData *)toJSONData;

@end

//
//  NSDictionary+JSON.m
//  Category
//
//  Created by YouXianMing on 15-2-09.
//  Copyright (c) 2014年 YouXianMing. All rights reserved.
//

#import "NSDictionary+JSON.h"

@implementation NSDictionary (JSON)

- (NSString *)toJSONString {
    NSData *data = [NSJSONSerialization dataWithJSONObject:self
                                                   options:NSJSONReadingMutableLeaves | NSJSONReadingAllowFragments
                                                     error:nil];
    
    if (data == nil) {
        return nil;
    }
    
    NSString *string = [[NSString alloc] initWithData:data
                                             encoding:NSUTF8StringEncoding];
    return string;
}

- (NSString *)toReadableJSONString {
    NSData *data = [NSJSONSerialization dataWithJSONObject:self
                                                   options:NSJSONWritingPrettyPrinted
                                                     error:nil];
    
    if (data == nil) {
        return nil;
    }
    
    NSString *string = [[NSString alloc] initWithData:data
                                             encoding:NSUTF8StringEncoding];
    return string;
}

- (NSData *)toJSONData {
    NSData *data = [NSJSONSerialization dataWithJSONObject:self
                                                   options:NSJSONWritingPrettyPrinted
                                                     error:nil];
    
    return data;
}

@end

NSArray+JSON.h 与 NSArray+JSON.m

//
//  NSArray+JSON.h
//  Category
//
//  Created by YouXianMing on 15-2-09.
//  Copyright (c) 2014年 YouXianMing. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface NSArray (JSON)

/**
 *  转换成JSON串字符串（没有可读性）
 *
 *  @return JSON字符串
 */
- (NSString *)toJSONString;

/**
 *  转换成JSON串字符串（有可读性）
 *
 *  @return JSON字符串
 */
- (NSString *)toReadableJSONString;

/**
 *  转换成JSON数据
 *
 *  @return JSON数据
 */
- (NSData *)toJSONData;

@end

//
//  NSArray+JSON.m
//  Category
//
//  Created by YouXianMing on 15-2-09.
//  Copyright (c) 2014年 YouXianMing. All rights reserved.
//

#import "NSArray+JSON.h"

@implementation NSArray (JSON)

- (NSString *)toJSONString {
    NSData *data = [NSJSONSerialization dataWithJSONObject:self
                                                   options:NSJSONReadingMutableLeaves | NSJSONReadingAllowFragments
                                                     error:nil];
    
    if (data == nil) {
        return nil;
    }
    
    NSString *string = [[NSString alloc] initWithData:data
                                             encoding:NSUTF8StringEncoding];
    return string;
}

- (NSString *)toReadableJSONString {
    NSData *data = [NSJSONSerialization dataWithJSONObject:self
                                                   options:NSJSONWritingPrettyPrinted
                                                     error:nil];
    
    if (data == nil) {
        return nil;
    }
    
    NSString *string = [[NSString alloc] initWithData:data
                                             encoding:NSUTF8StringEncoding];
    return string;
}

- (NSData *)toJSONData {
    NSData *data = [NSJSONSerialization dataWithJSONObject:self
                                                   options:NSJSONWritingPrettyPrinted
                                                     error:nil];
    
    return data;
}

@end

使用：