《慕客网：IOS基础入门之Foundation框架初体验》学习笔记 <五> NSDicionary + NSMutableDictionary

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        //字典， 存储的内存不是连续的 用key和value进行对应(键值)
        //kvc 键值编码
        NSDictionary *dic = [NSDictionary dictionaryWithObject:@"1" forKey:@"a"];
        NSLog(@"%@",dic);//以上的方法是不常用的
        //注意两个参数是数组
        //NSDictionary *dic2 = [NSDictionary dictionaryWithObjects:<#(NSArray *)#> forKeys:<#(NSArray *)#>]
        //所以还是要先创建两个数组
        NSArray *array1 = [[NSArray alloc] initWithObjects:@"a",@"b",@"c",@"d", nil];
        NSArray *array2 = [[NSArray alloc] initWithObjects:@"1",@"2",@"3",@"4", nil];
        NSDictionary *dic2 = [[NSDictionary alloc] initWithObjects:array1 forKeys:array2];
        NSLog(@"%@",dic2);
        //
        NSDictionary *dic3 = @{@"m":@"9",@"n":@"8"};
        NSLog(@"%@",dic3);
        //输出字典的长度
        int count = (int)[dic3 count];
        NSLog(@"%d",count);
        //通过键 获得 值
        NSString *str = [dic3 valueForKey:@"m"];//或者[dic3 objectForKey:@"m"]
        NSLog(@"%@",str);
        //获取所有键值中的键和值
        NSArray *allValue = [dic3 allValues];
        NSArray *allKey = [dic3 allKeys];
        //通过多个键找值，因为是多个，当然返回的是数组
        NSArray *array = [dic2 objectsForKeys:[NSArray arrayWithObjects:@"2",@"3",@"9", nil] notFoundMarker:@"not found"];
        NSLog(@"%@",array);
        //遍历字典，数组通过下标遍历，字典当然通过key来遍历
        for (NSString *key in dic2) {
            NSLog(@"%@ = %@",key,[dic2 objectForKey:key]);
        }
        //使用针对字典的枚举器
        NSEnumerator *en = [dic2 keyEnumerator];
        id key = nil;
        while (key = [en nextObject]) {
            NSLog(@"key - %@",key);
        }
        //还有一个block方法，用法都是一样的
        /*
        [dic2 enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
            
        }];*/
    }
    return 0;
}

 

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
        //添加键值对，直接添加就可以了
        [dict setObject:@"1" forKey:@"a"];
        [dict setObject:@"2" forKey:@"b"];
        [dict setObject:@"3" forKey:@"c"];
        NSLog(@"%@",dict);
        //删除键值对
        [dict removeObjectForKey:@"a"];
        NSLog(@"%@",dict);
        //还可以通过传入数组对象，对应删除数组元素对应的所有键
        [dict removeObjectsForKeys:[NSArray arrayWithObjects:@"a",@"c", nil]];
        NSLog(@"%@",dict);
    }
    return 0;
}