JSON

iOS中的解析方案：

第三方：JSONKit, SBJson, TouchJSON

苹果原生 NSJSONSerialization（性能最好）

NSJSONSerialization

JSON -> OC对象

- (void)jsonToOc
{
    NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/login?username=520it&pwd=520it&type=JSON"];

    NSURLRequest *request = [NSURLRequest requestWithURL:url];

    [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {

        /*
         * 参数1：json二进制数据
         * 参数2：
         * NSJSONReadingMutableContainers = (1UL << 0), 可变字典和数组
         * NSJSONReadingMutableLeaves = (1UL << 1), 内部所有字符串是可变的（iOS7以后有问题，一般用不到）
         * NSJSONReadingAllowFragments = (1UL << 2) 既不是字典也不是数组，使用这个枚举
         * 参数3：错误信息
         */
        NSMutableDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];

        NSLog(@"%@",dict);
    }];
}

JSON -> OC对象之间的数据转换关系

- (void)jsonWithOc
{
    NSString *str = @"\{\"error\":\"用户名不存在\"}"; //options:NSJSONReadingMutableContainers //输出： NSDictionary----{error = "\U7528\U6237\U540d\U4e0d\U5b58\U5728";}
    //NSString *str = @"[\"team1\",\"team2\"]"; //options:NSJSONReadingMutableContainers //输出： NSArray----(team1,team2)
    //NSString *str = @"\"fewcfrvfecwscd\""; //options:NSJSONReadingAllowFragments //输出： NSMutableString----fewcfrvfecwscd
    //NSString *str = @"false"; //options:NSJSONReadingAllowFragments //输出： NSNumber----1
    //NSString *str = @"true"; //options:NSJSONReadingAllowFragments //输出： NSNumber----1
    //NSString *str = @"null"; //options:NSJSONReadingAllowFragments //输出：superclass:NSObjcect  class:NSNull  value  <null>

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

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

总结以上特点：

OC对象 -> JSON

- (void)ocToJson
{
    NSDictionary *dictM = @{@"name":@"张帆",@"age":@32};

    /*
     * 参数1：要转换的OC对象
     * 参数2：
     * NSJSONWritingPrettyPrinted 排版美观
     * 参数3：错误信息
     */
    NSString *strM = @"vevrevverwcferw";
    BOOL isValid = [NSJSONSerialization isValidJSONObject:strM];
    /*
     - 最外层的对象必须是 NSArray or NSDictionary
     - 所有的元素必须是 NSString, NSNumber, NSArray, NSDictionary, or NSNull
     - 字典的键必须是 NSStrings
     - NSNumbers 不能为 NaN 或 infinity（无穷大）
     */
    if(!isValid)
    {
        NSLog(@"该数据类型无法转换为json");
        return;
    }
    NSData *data = [NSJSONSerialization dataWithJSONObject:dictM options:NSJSONWritingPrettyPrinted error:nil];
    NSLog(@"%@",[[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding]);
}

plist文件转json文件存储

- (void)plistFileToJsonFile
{
    NSString *path = [[NSBundle mainBundle] pathForResource:@"apps.plist" ofType:nil];

    NSArray *dicts = [NSArray arrayWithContentsOfFile:path];

    NSLog(@"%@",dicts);

    NSData *data = [NSJSONSerialization dataWithJSONObject:dicts options:NSJSONWritingPrettyPrinted error:nil];

    NSLog(@"%@",data);

    NSString *path2 = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];

    NSString *fileName = @"app.json";

    NSString *fullPath = [path2 stringByAppendingPathComponent:fileName];

    NSLog(@"%@",fullPath);
    [data writeToFile:fullPath atomically:YES];
}