iOS - OC - JSON 解析 - NSJSONSerialization

 #import "ViewController.h"

 @interface ViewController ()

 @end

 @implementation ViewController

 -(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
 {
     [self test];
 }

 -(void)jsonToOC
 {
     //1.确定url
     NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/login?username=123&pwd=456&type=JSON"];

     //2.创建请求对象
     NSURLRequest *request = [NSURLRequest requestWithURL:url];

     //3.发送异步请求
     [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {
         //data---->本质上是一个json字符串
         //4.解析数据
         //NSLog(@"%@",[[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding]);

         //JSON--->oc对象 反序列化
         /*
          第一个参数:JSON的二进制数据
          第二个参数:
          第三个参数:错误信息
          */
         /*
          NSJSONReadingMutableContainers = (1UL << 0), 可变字典和数组
          NSJSONReadingMutableLeaves = (1UL << 1),      内部所有的字符串都是可变的 ios7之后又问题  一般不用
          NSJSONReadingAllowFragments = (1UL << 2)   既不是字典也不是数组,则必须使用该枚举值
          */

         NSString *strM = @"\"wendingding\"";

         //        NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];

         id obj = [NSJSONSerialization JSONObjectWithData:[strM dataUsingEncoding:NSUTF8StringEncoding] options:NSJSONReadingAllowFragments error:nil];

         NSLog(@"%@---%@",[obj class],obj);

     }];

 }

 //JSON--->OC
 -(void)JSONWithOc
 {
     //NSString *strM = @"{\"error\":\"用户名不存在\"}";
     //NSString *strM = @"[\"error\",\"用户名不存在\"]";
     //NSString *strM = @"\"wendingding\"";
     //NSString *strM = @"false";
     //NSString *strM = @"true";
     NSString *strM = @"null";

     id obj = [NSJSONSerialization JSONObjectWithData:[strM dataUsingEncoding:NSUTF8StringEncoding] options:NSJSONReadingAllowFragments error:];
     NSLog(@"%@---%@",[obj class],obj);

     /*
      JOSN   OC
      {}     @{}
      []     @[]
      ""     @""
      false  NSNumber 0
      true   NSNumber 1
      null      NSNull为空
      */

     //nil
     [NSNull null];   //该方法获得的是一个单粒,表示为空,可以用在字典或者是数组中

 }

 //OC--->json
 -(void)OCtojson
 {
     NSDictionary *dictM = @{
                             @"name":@"dasheng11",
                             @"age":@
            };

     NSArray *arrayM = @[@"",@""];

     //注意:并不是所有的OC对象都能转换为JSON
     /*
      - 最外层必须是 NSArray or NSDictionary
      - 所有的元素必须是 NSString, NSNumber, NSArray, NSDictionary, or NSNull
      - 字典中所有的key都必须是 NSStrings类型的
      - NSNumbers不能死无穷大
      */
     NSString *strM = @"WENIDNGDING";

     BOOL isValid = [NSJSONSerialization isValidJSONObject:strM];
     if (!isValid) {
         NSLog(@"%zd",isValid);
         return;
     }

     //OC--->json
     /*
      第一个参数:要转换的OC对象
      第二个参数:选项NSJSONWritingPrettyPrinted 排版 美观
      */
     NSData *data = [NSJSONSerialization dataWithJSONObject:strM options:NSJSONWritingPrettyPrinted error:nil];

     NSLog(@"%@",[[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding]);
 }

 -(void)test
 {
     NSArray *arrayM = [NSArray arrayWithContentsOfFile:@"/Users/xiaomage/Desktop/课堂共享/11大神班上课资料/05-多线程网络/0225/资料/apps.plist"];
     NSLog(@"%@",arrayM);

     //[arrayM writeToFile:@"/Users/xiaomage/Desktop/123.json" atomically:YES];

     //OC--->JSON
     NSData *data =  [NSJSONSerialization dataWithJSONObject:arrayM options:NSJSONWritingPrettyPrinted error:];
     [data writeToFile:@"/Users/xiaomage/Desktop/123.json" atomically:YES];
 }