OC语法--字典类

#pragma mark 创建字典

void dictCreate() {
    //NSDictionary是不可变的
    NSDictionary *dict = [NSDictionary dictionaryWithObject:@"v" forKey:@"k"];
    //最常用的初始化方式
    dict = [NSDictionary dictionaryWithObjectsAndKeys:
            @"v1",@"k1",
            @"v2",@"k2",
            @"v3",@"k3",
            nil];
    NSArray *objs = [NSArray arrayWithObjects:@"v1",@"v2",@"v3",nil];
    NSArray *keys = [NSArray arrayWithObjects:@"k2",@"k3",@"k4",nil];
    dict = [NSDictionary dictionaryWithObjects:objs forKeys:keys];

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

将字典写入文件，从文件读取：

void dicUse(){
    //NSDictionary是不可变的
    NSDictionary *dict = [NSDictionary dictionaryWithObject:@"v" forKey:@"k"];
    //最常用的初始化方式
    dict = [NSDictionary dictionaryWithObjectsAndKeys:
            @"v1",@"k0",
            @"v2",@"k2",
            @"v3",@"k3",
            nil];
    //返回字典键值对
    NSLog(@"count=%zi",dict.count);

    //dictionary不可变，所以只能取值，不能修改
    id obj = [dict objectForKey:@"k3"];
    NSLog(@"obj=%@",obj);
    NSLog(@"%@",dict);

    //将字典写入文件
    NSString *path = @"/Users/luteresa/Desktop/dic.txt";
    //[dict writeToFile:path atomically:YES];
    dict = [NSDictionary dictionaryWithContentsOfFile:path];
    NSLog(@"-%@",dict);
}

获取多个字典值：

void dictUse2(){
    //NSDictionary是不可变的
    NSDictionary *dict = [NSDictionary dictionaryWithObject:@"v" forKey:@"k"];
    //最常用的初始化方式
    dict = [NSDictionary dictionaryWithObjectsAndKeys:
            @"v1",@"k0",
            @"v1",@"k2",
            @"v3",@"k3",
            nil];
    //返回字典键值对
    NSLog(@"count=%zi",dict.count);

    //返回所有的key
    NSArray *keys = [dict allKeys];
    NSLog(@"keys=%@",keys);

    //返回所有的value
    NSArray *objs = [dict allValues];
    NSLog(@"%@",objs);
    keys =[dict allKeysForObject:@"v1"];
    NSLog(@"keys=%@",keys);

    //根据多个key取出对应的多个value
    //当key找不到value时，用marker代替
    objs = [dict objectsForKeys: [NSArray arrayWithObjects:@"k1",@"k2",nil] notFoundMarker:@"h"];
    NSLog(@"%@",objs);

}

遍历字典：

void dicFor(){
    //NSDictionary是不可变的
    NSDictionary *dict = [NSDictionary dictionaryWithObject:@"v" forKey:@"k"];
    //最常用的初始化方式
    dict = [NSDictionary dictionaryWithObjectsAndKeys:
            @"v1",@"k0",
            @"v1",@"k2",
            @"v3",@"k3",
            nil];

    for (id key in dict) {
        id value = [dict objectForKey:key];
        NSLog(@"%@->%@",key,value);
    }
}

用key迭代器遍历字典：

void dicFor2(){
    //NSDictionary是不可变的
    NSDictionary *dict = [NSDictionary dictionaryWithObject:@"v" forKey:@"k"];
    //最常用的初始化方式
    dict = [NSDictionary dictionaryWithObjectsAndKeys:
            @"v1",@"k0",
            @"v1",@"k2",
            @"v3",@"k3",
            nil];
    //key 迭代器
    NSEnumerator *enumerator = [dict keyEnumerator];
    id key = nil;
    while (key = [enumerator nextObject]) {
        id value = [dict objectForKey:key];
        NSLog(@"%@->%@",key,value);
    }
    //
}

用block迭代

void dicFor3(){
    //NSDictionary是不可变的
    NSDictionary *dict = [NSDictionary dictionaryWithObject:@"v" forKey:@"k"];
    //最常用的初始化方式
    dict = [NSDictionary dictionaryWithObjectsAndKeys:
            @"v1",@"k0",
            @"v1",@"k2",
            @"v3",@"k3",
            nil];
    [dict enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
        NSLog(@"%@=%@",key,obj);
    }];


}

NSMutableDictionary:字典子集，可变

void dicMutUse(){
    NSMutableDictionary *dict = [NSMutableDictionary dictionary];
    Student *stu1 = [Student studentWithName:@"name1"];
    Student *stu2 = [Student studentWithName:@"name2"];

    [dict setObject:stu1 forKey:@"k1"];
    [dict setObject:stu2 forKey:@"k2"];
    NSLog(@"retain:%zi",[stu1 retainCount]);

    NSLog(@"%@->%@",@"k1",[[dict objectForKey:@"k1"] name]);
    //[dict removeAllObjects];
    //[dict removeObjectForKey:@"k1"];
    NSLog(@"retain:%zi",[stu1 retainCount]);
   // NSLog(@"%@",stu1);

    //添加其他字典
    NSDictionary *other = [NSDictionary dictionaryWithObject:@"name3" forKey:@"k3"];
    [dict addEntriesFromDictionary:other];
    NSLog(@"count is %zi",[dict count]);

    //NSLog(@"%@->%@",@"k3",[dict objectForKey:@"k3"]);
}