iOS_XML与JSON解析

XML与JSON简介

XML

可扩展标记语言
用于标记电子文件使其具有结构性的标记语言，可以用来标记数据、定义数据类型，是一种允许用户对自己的标记语言进行定义的源语言
易读性高，编码手写难度小，数据量大

NSXMLParser解析方法

我们所用到的NSXMLParser是采用SAX方法解析

SAX（Simple API for XML）

只能读，不能修改，只能顺序访问，适合解析大型XML，解析速度快
常应用于处理大量数据的XML，实现异构系统的数据访问，实现跨平台
从文档的开始通过每一节点移动，定位一个特定的节点

DOM（Document Object Model）

不仅能读，还能修改，而且能够实现随机访问，缺点是解析速度慢，适合解析小型文档
一般应用与小型的配置XML，方便操作
为载入到内存的文档节点建立类型描述，呈现可横向移动、潜在巨大的树型结构
在内存中生成节点树操作代价昂贵

xmlParser解析过程

NSXMLParser解析过程

1.创建NSXMLParser实例，并传入从服务器接收的XML数据

2.定义解析器代理

3.解析器解析

4.通过解析代理方法完成XML数据的解析

使用XML解析文档时使用协议<NSXMLParserDelegate>，实现它的代理方法

// 1. 开始解析某个元素，会遍历整个XML，识别元素节点名称

- (void)parser:didStartElement:namespaceURI:qualifiedName:attributes:

// 2. 文本节点，得到文本节点里存储的信息数据，对于大数据可能会接收多次！为了节约内存开销

- (void)parser:foundCharacters:

// 3. 结束某个节点，存储从parser:foundCharacters:方法中获取到的信息

- (void)parser:didEndElement:namespaceURI:qualifiedName:

注意：在解析过程中，上述三个方法会不停的重复执行，直到遍历完成为止

// 4. 开始解析XML文档

- (void)parserDidStartDocument:

// 5. 解析XML文档结束

- (void)parserDidEndDocument:

// 6. 解析出错

- (void)parser:parseErrorOccurred:

接下来通过案例来详细分析XML的解析

 1 #import "ViewController.h"
 2 #import "Student.h"
 3 @interface ViewController ()<NSXMLParserDelegate>
 4 //student数组
 5 @property(strong,nonatomic)NSMutableArray *students;
 6 @property(strong,nonatomic)Student *currentStudent;
 7 //当前的元素名
 8 @property(strong,nonatomic)NSString *elementName;
 9 //元素值
10 @property(strong,nonatomic)NSMutableString *elementValue;
11 @end
12 
13 @implementation ViewController
14 //XMLParse解析过程
15 -(void)XMLParse
16 {
17     //1.从网络上获取xml文件数据
18     NSData *xmlData = [NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://127.0.0.1/userManager/student.xml"]];
19     //2.创建XML解析对象
20     NSXMLParser *parser = [[NSXMLParser alloc]initWithData:xmlData];
21     //3.设置代理
22     parser.delegate = self;
23     //4.开始解析
24     [parser parse];
25 }
26 - (void)viewDidLoad {
27     [super viewDidLoad];
28     //调用解析方法
29     [self XMLParse];
30 }
31 #pragma mark - NSXMLParser代理方法
32 //开始解析，解析的准备工作
33 -(void)parserDidStartDocument:(NSXMLParser *)parser
34 {
35     self.students = [NSMutableArray array];
36 }
37 //解析XML结束，输出文档的内容
38 -(void)parserDidEndDocument:(NSXMLParser *)parser
39 {
40     NSLog(@"%@",self.students);
41 }
42 //开始解析某个元素，会遍历整个XML，识别元素结点名称
43 -(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
44 {
45     if ([elementName isEqualToString:@"student"])
46     {
47         //创建新的对象
48         self.currentStudent = [[Student alloc]init];
49     }
50     else if([elementName isEqualToString:@"name"]||
51             [elementName isEqualToString:@"age"]||
52             [elementName isEqualToString:@"sex"])
53     {
54         self.elementValue = [[NSMutableString alloc]init];
55     }
56 }
57 //文本节点，得到文本节点里存储的信息数据，对于大数据可能会接收多次，
58 -(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
59 {
60     //将找到的字符，跟已取的字符进行拼接
61     [self.elementValue appendString:string];
62 }
63 //结束某个节点，存储获取到的信息
64 -(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
65 {
66     if ([elementName isEqualToString:@"name"])
67     {
68         //将读取到的元素值，赋值给对应的属性名
69         self.currentStudent.name = self.elementValue;
70     }
71     else if ([elementName isEqualToString:@"age"])
72     {
73         self.currentStudent.age = [self.elementValue integerValue];
74     }
75     else if([elementName isEqualToString:@"sex"])
76     {
77         self.currentStudent.sex = [self.elementValue characterAtIndex:0];
78     }
79     else if ([elementName isEqualToString:@"student"])
80     {
81         if (self.currentStudent)
82         {
83             [self.students addObject:self.currentStudent];
84         }
85     }
86 }
87 //差错解析
88 -(void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError
89 {
90     NSLog(@"Error reason:%@",parseError);
91 }
92 @end

下面这个案例就是实现citier.xml的解析

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>provinces</key>
    <array>
        <string>安徽</string>
        <string>澳门</string>
        <string>北京</string>
        <string>重庆</string>
        <string>福建</string>
        <string>甘肃</string>
        <string>广东</string>
        <string>广西</string>
        <string>贵州</string>
        <string>海南</string>
        <string>河北</string>
        <string>河南</string>
        <string>黑龙江</string>
        <string>湖北</string>
        <string>湖南</string>
        <string>吉林</string>
        <string>江苏</string>
        <string>江西</string>
        <string>辽宁</string>
        <string>内蒙古</string>
        <string>宁夏</string>
        <string>青海</string>
        <string>山东</string>
        <string>山西</string>
        <string>陕西</string>
        <string>上海</string>
        <string>四川</string>
        <string>台湾</string>
        <string>天津</string>
        <string>西藏</string>
        <string>香港</string>
        <string>新疆</string>
        <string>云南</string>
        <string>浙江</string>
    </array>
    <key>cities</key>
    <dict>
        <key>北京</key>
        <array>
            <string>东城区</string>
            <string>西城区</string>
            <string>崇文区</string>
            <string>宣武区</string>
            <string>海淀区</string>
            <string>朝阳区</string>
            <string>丰台区</string>
            <string>石景山区</string>
            <string>通州区</string>
            <string>顺义区</string>
            <string>房山区</string>
            <string>大兴区</string>
            <string>昌平区</string>
            <string>怀柔区</string>
            <string>平谷区</string>
            <string>门头沟区</string>
            <string>密云县</string>
            <string>延庆县</string>
        </array>
        <key>重庆</key>
        <array>
            <string>重庆</string>
        </array>
        <key>上海</key>
        <array>
            <string>上海</string>
        </array>
        <key>天津</key>
        <array>
            <string>天津</string>
        </array>
        <key>安徽</key>
        <array>
            <string>合肥</string>
            <string>安庆</string>
            <string>蚌埠</string>
            <string>亳州</string>
            <string>巢湖</string>
            <string>池州</string>
            <string>滁州</string>
            <string>阜阳</string>
            <string>淮北</string>
            <string>淮南</string>
            <string>黄山</string>
            <string>黄山景区</string>
            <string>九华山景区</string>
            <string>六安</string>
            <string>马鞍山</string>
            <string>青阳</string>
            <string>宿州</string>
            <string>铜陵</string>
            <string>芜湖</string>
            <string>宣城</string>
        </array>
        <key>福建</key>
        <array>
            <string>福州</string>
            <string>龙岩</string>
            <string>南平</string>
            <string>宁德</string>
            <string>莆田</string>
            <string>泉州</string>
            <string>三明</string>
            <string>厦门</string>
            <string>永安</string>
            <string>漳州</string>
        </array>
        <key>广东</key>
        <array>
            <string>广州</string>
            <string>潮州</string>
            <string>从化</string>
            <string>东莞</string>
            <string>佛山</string>
            <string>河源</string>
            <string>鹤山</string>
            <string>化州</string>
            <string>惠州</string>
            <string>江门</string>
            <string>揭阳</string>
            <string>茂名</string>
            <string>梅州</string>
            <string>清远</string>
            <string>汕头</string>
            <string>汕尾</string>
            <string>韶关</string>
            <string>深圳</string>
            <string>阳江</string>
            <string>云浮</string>
            <string>湛江</string>
            <string>肇庆</string>
            <string>中山</string>
            <string>珠海</string>
        </array>
        <key>甘肃</key>
        <array>
            <string>兰州</string>
            <string>白银</string>
            <string>定西</string>
            <string>甘南</string>
            <string>嘉峪关</string>
            <string>酒泉</string>
            <string>临夏</string>
            <string>陇南</string>
            <string>平凉</string>
            <string>庆阳</string>
            <string>天水</string>
            <string>武威</string>
            <string>张掖</string>
        </array>
        <key>广西</key>
        <array>
            <string>南宁</string>
            <string>百色</string>
            <string>北海</string>
            <string>北流</string>
            <string>崇左</string>
            <string>防城港</string>
            <string>贵港</string>
            <string>桂林</string>
            <string>桂平</string>
            <string>河池</string>
            <string>贺州</string>
            <string>来宾</string>
            <string>柳州</string>
            <string>钦州</string>
            <string>梧州</string>
            <string>宜州</string>
            <string>玉林</string>
        </array>
        <key>贵州</key>
        <array>
            <string>贵阳</string>
            <string>安顺</string>
            <string>毕节</string>
            <string>都匀</string>
            <string>凯里</string>
            <string>六盘水</string>
            <string>铜仁</string>
            <string>兴义</string>
            <string>遵义</string>
        </array>
        <key>河北</key>
        <array>
            <string>石家庄</string>
            <string>保定</string>
            <string>泊头</string>
            <string>沧州</string>
            <string>承德</string>
            <string>邯郸</string>
            <string>河间</string>
            <string>衡水</string>
            <string>廊坊</string>
            <string>秦皇岛</string>
            <string>任丘</string>
            <string>唐山</string>
            <string>邢台</string>
            <string>张家口</string>
        </array>
        <key>河南</key>
        <array>
            <string>郑州</string>
            <string>安阳</string>
            <string>鹤壁</string>
            <string>济源</string>
            <string>焦作</string>
            <string>开封</string>
            <string>洛阳</string>
            <string>漯河</string>
            <string>南阳</string>
            <string>平顶山</string>
            <string>濮阳</string>
            <string>三门峡</string>
            <string>商丘</string>
            <string>新乡</string>
            <string>信阳</string>
            <string>许昌</string>
            <string>周口</string>
            <string>驻马店</string>
        </array>
        <key>黑龙江</key>
        <array>
            <string>哈尔滨</string>
            <string>大庆</string>
            <string>大兴安岭</string>
            <string>鹤岗</string>
            <string>黑河</string>
            <string>虎林</string>
            <string>鸡西</string>
            <string>佳木斯</string>
            <string>密山</string>
            <string>牡丹江</string>
            <string>宁安</string>
            <string>七台河</string>
            <string>齐齐哈尔</string>
            <string>双鸭山</string>
            <string>绥化</string>
            <string>五常</string>
            <string>伊春</string>
        </array>
        <key>湖北</key>
        <array>
            <string>武汉</string>
            <string>鄂州</string>
            <string>恩施</string>
            <string>黄冈</string>
            <string>黄石</string>
            <string>荆门</string>
            <string>荆州</string>
            <string>潜江</string>
            <string>十堰</string>
            <string>随州</string>
            <string>天门</string>
            <string>仙桃</string>
            <string>咸宁</string>
            <string>襄樊</string>
            <string>孝感</string>
            <string>宜昌</string>
        </array>
        <key>湖南</key>
        <array>
            <string>长沙</string>
            <string>常德</string>
            <string>郴州</string>
            <string>衡阳</string>
            <string>怀化</string>
            <string>吉首</string>
            <string>耒阳</string>
            <string>冷水江</string>
            <string>娄底</string>
            <string>韶山</string>
            <string>邵阳</string>
            <string>湘潭</string>
            <string>湘乡</string>
            <string>益阳</string>
            <string>永州</string>
            <string>岳阳</string>
            <string>张家界</string>
            <string>株州</string>
        </array>
        <key>吉林</key>
        <array>
            <string>长春</string>
            <string>白城</string>
            <string>白山</string>
            <string>珲春</string>
            <string>吉林</string>
            <string>辽源</string>
            <string>龙井</string>
            <string>舒兰</string>
            <string>四平</string>
            <string>松原</string>
            <string>通化</string>
            <string>延边</string>
        </array>
        <key>江苏</key>
        <array>
            <string>南京</string>
            <string>常州</string>
            <string>高邮</string>
            <string>淮安</string>
            <string>连云港</string>
            <string>南通</string>
            <string>苏州</string>
            <string>宿迁</string>
            <string>太仓</string>
            <string>泰州</string>
            <string>无锡</string>
            <string>新沂</string>
            <string>徐州</string>
            <string>盐城</string>
            <string>扬州</string>
            <string>镇江</string>
        </array>
        <key>江西</key>
        <array>
            <string>南昌</string>
            <string>抚州</string>
            <string>赣州</string>
            <string>吉安</string>
            <string>景德镇</string>
            <string>九江</string>
            <string>萍乡</string>
            <string>上饶</string>
            <string>新余</string>
            <string>宜春</string>
            <string>鹰潭</string>
        </array>
        <key>辽宁</key>
        <array>
            <string>沈阳</string>
            <string>鞍山</string>
            <string>本溪</string>
            <string>朝阳</string>
            <string>大连</string>
            <string>丹东</string>
            <string>抚顺</string>
            <string>阜新</string>
            <string>葫芦岛</string>
            <string>锦州</string>
            <string>辽阳</string>
            <string>盘锦</string>
            <string>铁岭</string>
            <string>营口</string>
        </array>
        <key>内蒙古</key>
        <array>
            <string>呼和浩特</string>
            <string>阿拉善盟</string>
            <string>巴彦淖尔盟</string>
            <string>包头</string>
            <string>赤峰</string>
            <string>鄂尔多斯</string>
            <string>呼伦贝尔</string>
            <string>通辽</string>
            <string>乌海</string>
            <string>乌兰察布盟</string>
            <string>锡林郭勒盟</string>
            <string>兴安盟</string>
        </array>
        <key>宁夏</key>
        <array>
            <string>银川</string>
            <string>固原</string>
            <string>石嘴山</string>
            <string>吴忠</string>
            <string>中卫</string>
        </array>
        <key>青海</key>
        <array>
            <string>西宁</string>
            <string>果洛</string>
            <string>海北</string>
            <string>海东</string>
            <string>海南</string>
            <string>海西</string>
            <string>黄南</string>
            <string>玉树</string>
        </array>
        <key>四川</key>
        <array>
            <string>成都</string>
            <string>阿坝</string>
            <string>巴中</string>
            <string>崇州</string>
            <string>达州</string>
            <string>大邑</string>
            <string>德阳</string>
            <string>都江堰</string>
            <string>峨眉山</string>
            <string>甘孜</string>
            <string>广安</string>
            <string>广元</string>
            <string>江油</string>
            <string>金堂</string>
            <string>乐山</string>
            <string>泸州</string>
            <string>眉山</string>
            <string>绵阳</string>
            <string>内江</string>
            <string>南充</string>
            <string>攀枝花</string>
            <string>遂宁</string>
            <string>西昌</string>
            <string>雅安</string>
            <string>宜宾</string>
            <string>资阳</string>
            <string>自贡</string>
        </array>
        <key>山东</key>
        <array>
            <string>济南</string>
            <string>滨州</string>
            <string>德州</string>
            <string>东营</string>
            <string>肥城</string>
            <string>海阳</string>
            <string>菏泽</string>
            <string>济宁</string>
            <string>莱芜</string>
            <string>莱阳</string>
            <string>聊城</string>
            <string>临沂</string>
            <string>平度</string>
            <string>青岛</string>
            <string>青州</string>
            <string>日照</string>
            <string>泰安</string>
            <string>威海</string>
            <string>潍坊</string>
            <string>烟台</string>
            <string>枣庄</string>
            <string>章丘</string>
            <string>淄博</string>
        </array>
        <key>陕西</key>
        <array>
            <string>西安</string>
            <string>安康</string>
            <string>宝鸡</string>
            <string>汉中</string>
            <string>商洛</string>
            <string>铜川</string>
            <string>渭南</string>
            <string>咸阳</string>
            <string>兴平</string>
            <string>延安</string>
            <string>榆林</string>
        </array>
        <key>山西</key>
        <array>
            <string>太原</string>
            <string>长治</string>
            <string>大同</string>
            <string>晋城</string>
            <string>晋中</string>
            <string>临汾</string>
            <string>吕梁</string>
            <string>朔州</string>
            <string>忻州</string>
            <string>阳泉</string>
            <string>运城</string>
        </array>
        <key>新疆</key>
        <array>
            <string>乌鲁木齐</string>
            <string>阿克苏</string>
            <string>阿拉尔</string>
            <string>阿图什</string>
            <string>博乐</string>
            <string>昌吉</string>
            <string>哈密</string>
            <string>和田</string>
            <string>喀什</string>
            <string>克拉玛依</string>
            <string>库尔勒</string>
            <string>石河子</string>
            <string>图木舒克</string>
            <string>吐鲁番</string>
            <string>五家渠</string>
            <string>伊宁</string>
        </array>
        <key>西藏</key>
        <array>
            <string>拉萨</string>
            <string>阿里</string>
            <string>昌都</string>
            <string>林芝</string>
            <string>那曲</string>
            <string>日喀则</string>
            <string>山南</string>
        </array>
        <key>云南</key>
        <array>
            <string>昆明</string>
            <string>保山</string>
            <string>楚雄</string>
            <string>大理</string>
            <string>德宏</string>
            <string>迪庆</string>
            <string>个旧</string>
            <string>丽江</string>
            <string>临沧</string>
            <string>怒江</string>
            <string>曲靖</string>
            <string>思茅</string>
            <string>文山</string>
            <string>西双版纳</string>
            <string>玉溪</string>
            <string>昭通</string>
        </array>
        <key>浙江</key>
        <array>
            <string>杭州</string>
            <string>北仑</string>
            <string>慈溪</string>
            <string>奉化</string>
            <string>湖州</string>
            <string>嘉兴</string>
            <string>金华</string>
            <string>丽水</string>
            <string>临海</string>
            <string>宁波</string>
            <string>宁海</string>
            <string>衢州</string>
            <string>三门</string>
            <string>绍兴</string>
            <string>台州</string>
            <string>天台</string>
            <string>温岭</string>
            <string>温州</string>
            <string>仙居</string>
            <string>象山</string>
            <string>义乌</string>
            <string>余姚</string>
            <string>舟山</string>
        </array>
        <key>澳门</key>
        <array>
            <string>澳门</string>
        </array>
        <key>台湾</key>
        <array>
            <string>台北</string>
            <string>高雄</string>
            <string>台南</string>
            <string>台中</string>
        </array>
        <key>香港</key>
        <array>
            <string>香港</string>
        </array>
        <key>海南</key>
        <array>
            <string>海口</string>
            <string>儋州</string>
            <string>东方</string>
            <string>琼海</string>
            <string>三亚</string>
            <string>万宁</string>
            <string>文昌</string>
            <string>五指山</string>
        </array>
    </dict>
</dict>
</plist>

cities.xml

实现代码如下：

 1 #import "ViewController.h"
 2 
 3 @interface ViewController ()<NSXMLParserDelegate>
 4 @property(strong,nonatomic)NSMutableDictionary *dic;
 5 @property(strong,nonatomic)NSMutableArray *array;
 6 @property(strong,nonatomic)NSMutableDictionary *cities;
 7 @property(strong,nonatomic)NSString *keyName;
 8 @property(strong,nonatomic)NSMutableString *elementValue;
 9 
10 @end
11 
12 @implementation ViewController
13 
14 - (void)viewDidLoad {
15     [super viewDidLoad];
16     [self XMLParser];
17 }
18 
19 -(void)XMLParser
20 {
21     //1.获取网络数据
22     NSData *xmlData = [NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://127.0.0.1/userManager/cities.xml"]];
23     //2.创建解析对象
24     NSXMLParser *parser = [[NSXMLParser alloc]initWithData:xmlData];
25     //3.设置代理
26     parser.delegate = self;
27     //4.开始解析
28     [parser parse];
29 }
30 #pragma mark - NSXMLParser代理方法
31 //文档开始
32 -(void)parserDidStartDocument:(NSXMLParser *)parser
33 {
34     self.dic = [NSMutableDictionary dictionary];
35 }
36 //文档结束
37 -(void)parserDidEndDocument:(NSXMLParser *)parser
38 {
39     [self.dic setObject:self.cities forKey:@"cities"];
40     NSLog(@"%@",self.dic);
41 }
42 //元素开始
43 -(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
44 {
45     if ([elementName isEqualToString:@"array"])
46     {
47         self.array = [NSMutableArray array];
48     }
49     else if ([elementName isEqualToString:@"dict"])
50     {
51         if ([self.keyName hasPrefix:@"cities"])
52         {
53             self.cities = [NSMutableDictionary dictionary];
54         }
55     }
56     else if ([elementName isEqualToString:@"string"]||
57              [elementName isEqualToString:@"key"])
58     {
59         self.elementValue = [[NSMutableString alloc]init];
60     }
61 }
62 //元素结束
63 -(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
64 {
65     if ([elementName isEqualToString:@"array"])
66     {
67         if ([self.keyName hasPrefix:@"provinces"])
68         {
69             [self.dic setObject:self.array forKey:self.keyName];
70         }
71         else
72         {
73             [self.cities setObject:self.array forKey:self.keyName];
74         }
75     }
76     else if ([elementName isEqualToString:@"key"])
77     {
78         self.keyName = self.elementValue;
79     }
80     else if ([elementName isEqualToString:@"string"])
81     {
82         [self.array addObject:self.elementValue];
83     }
84     
85 }
86 //找字符
87 -(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
88 {
89     [self.elementValue appendString:string];
90 }
91 //出错解析
92 -(void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError
93 {
94     NSLog(@"error reason:%@",parseError);
95 }
96 @end

JSON

作为一种轻量级的数据交换格式，正在逐步取代XML，成为网络数据的通用格式
基于JavaScript的一个子集
易读性略差，编码手写难度大，数据量小
JSON格式取代了XML给网络传输带来了很大的便利，但是却没有了XML的一目了然，尤其是JSON数据很长的时候，我们会陷入繁琐复杂的数据节点查找中
作为一种轻量级的数据交换格式，JSON正在逐步取代XML，成为网络数据的通用格式。废话不多说，直接上代码。

案例1:使用NSDictionary创建JSON文件

 1 -(void)dataFromJSONObject
 2 {
 3     //从网络数据生成字典
 4     NSDictionary *dic = [NSDictionary dictionaryWithContentsOfURL:[NSURL URLWithString:@"http://127.0.0.1/userManager/cities.xml"]];
 5     NSError *error = nil;
 6     //将字典转换成JSON数据
 7     //    NSJSONWritingPrettyPrinted：的意思是将生成的json数据格式化输出，这样可读性高，不设置则输出的json字符串就是一整行。
 8     NSData *data = [NSJSONSerialization dataWithJSONObject:dic options:NSJSONWritingPrettyPrinted error:&error];
 9     if (!error)
10     {
11         //拼接路径
12         NSString *document = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
13         NSLog(@"%@",document);
14         NSString *jsonPath = [document stringByAppendingPathComponent:@"cities.json"];
15         //将数据写入文件中
16         [[NSFileManager defaultManager]createFileAtPath:jsonPath contents:data attributes:nil];
17     }
18 }

案例2：读取已有的JSON文件内容

 1 -(void)JSONObjectFromData
 2 {
 3     NSURL *url = [NSURL URLWithString:@"http://127.0.0.1/userManager/cities.json"];
 4     NSData *data = [NSData dataWithContentsOfURL:url];
 5     NSError *error = nil;
 6     //读取文件内容
 7     id obj = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:&error];
 8     if (!error)
 9     {
10         //判断对象的类型
11         if ([obj isKindOfClass:[NSDictionary class]])
12         {
13             NSDictionary *dic = obj;
14             NSLog(@"dic");
15             NSArray *provinces = [dic objectForKey:@"provinces"];
16             [provinces enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop)
17             {
18                 NSLog(@"%@",obj);
19             }];
20         }
21         else if ([obj isKindOfClass:[NSArray class]])
22         {
23             NSArray *array = obj;
24             NSLog(@"array");
25         }
26     }
27 }