iOS开发学习专题-基础知识(三)NSDictionary字典NSMutableDictionary可变字典NSDictionary字典和json转换详细使用方式

#pragma mark NSDictionary 不可变字典
    // NSDictionary用于键值映射
    // 1.字典的初始化(常见的几种方式)
    NSDictionary *dic1 = [NSDictionary dictionaryWithObject:@"@123" forKey:@"key1"];
    NSDictionary *dic2 = [NSDictionary dictionaryWithObjectsAndKeys:@"value1",@"key1",@"value2",@"key2" ,nil];
    NSDictionary *dic3 = [NSDictionary dictionaryWithDictionary:dic1];
    NSDictionary *dic4 = @{@"key1": @"value1",@"key2": @"value2"};
    NSString * path = @"路径";
    NSDictionary *dic5 = [NSDictionary dictionaryWithContentsOfFile:path];

    // 2.字典的常用操作
    // key - value ;输入的时候 [值 - 键]
    NSLog(@"%@",dic1);
    //输出的时候 为 [键 - 值];
    
    //2.值得获取和遍历
        // 2.1
        NSArray *key = [dic1 allKeys];
        NSLog(@"%@", key);
        
        // 2.2获取所有value值
        NSArray *value = [dic1 allValues];
        NSLog(@"%@", value);
        
        // 2.3通过key查询value
        NSString *name = [dic1 objectForKeyedSubscript:@"name"];
        NSLog(@"%@", name);//查找name key 对应的 value 值
        
        // 2.4根据allkeys数组获取字典中所有的key - value对
            //间接遍历
            for (NSString *key1 in key) {
                NSString *value = [dic1 objectForKey:key1];
                NSLog(@"%@ = %@:", key1 ,value);
            }
            //直接遍历
            for (NSString *key1 in dic1) {
                NSString *value = [dic1 objectForKey:key1];
                NSLog(@"%@ = %@", key1 ,value);
            }

#pragma mark NSMutableDictionary 可变字典
    //NSMutableDictionary
        //1.创建初始化
        NSMutableDictionary * mdic = [NSMutableDictionary dictionaryWithDictionary:dic2];
        //通过不可变的dic1传来的值,创建可变的字典
        
        //2.添加键值对 和 设定
            // 2.1添加一个指定键值对
            [mdic setValue:@"wu dang" forKey:@"attribute"];
            NSLog(@"%@", mdic);
            // 2.2像字典中添加整个字典对象
            [mdic addEntriesFromDictionary:dic1];
            // 2.3把字典内容设置与指定字典的内容相同
            [mdic setDictionary:dic1];
    
        //3.修改key 对应的value
        [mdic setValue:@"shan jia" forKey:@"hobby"];
        NSLog(@"%@", mdic);
        
        //4.删除键值对
            // 4.1删除制定键值对
            [mdic removeObjectForKey:@"sex"];
            NSLog(@"%@", dic2);
            // 4.2删除在数组中包含的指定key的对应的值
            NSArray *array = @[@"key1",@"key2",@"key3"];
            [mdic removeObjectsForKeys:array];
            // 4.3删除字典中的所有对象
            [mdic removeAllObjects];

#pragma mark NSDictionary 和 json 的互相转化
    // 1.字典转成json
    NSDictionary *jsondic = [NSDictionary dictionaryWithObjectsAndKeys:
                          @"zhang san",@"name",
                          @"men",@"sex",
                          @"playgame",@"hobby",
                          @"347",@"age",nil];
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:jsondic options:NSJSONWritingPrettyPrinted error:nil];
    NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
    
    // 2.json转成字典
    NSData *data =  [jsonString dataUsingEncoding:NSASCIIStringEncoding];
    NSDictionary * jsonObject = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:nil];