NSDictionary

//key - value 键值对 //初始化 NSDictionary *dictionary1 = [[NSDictionary alloc] initWithObjectsAndKeys:@"one",@"1",@"two",@"2", nil]; NSLog(@"%@",dictionary1); // NSDictionary *dictionary2 = [NSDictionary dictionaryWithObjectsAndKeys:<#(nonnull id), ...#>, nil] //字典的快速生成 NSDictionary *dictionary3 = @{@"1":@"one",@"2":@"two"}; NSLog(@"%@",dictionary3); //键值对的个数 NSLog(@"%ld", dictionary1.count); //查询一个对象 NSLog(@"obj = %@",[dictionary1 objectForKey:@"2"]); NSLog(@"obj1 = %@",dictionary1[@"2"]); //取出所有的key NSArray *keys = dictionary1.allKeys; //取出所有的对象 NSArray *values = dictionary1.allValues; NSLog(@"%@",values);

字典的遍历

/ /因为字典是以key-value形式存在，所以不可以直接遍历出一对，只能keys 或 value //字典是无序的 for (int i = 0; i <dictionary1.count ; i++) { id key = keys[i]; NSLog(@"%@",dictionary1[key]); } //根据key,遍历所有的value for (id object in dictionary1) { NSLog(@"%@",dictionary1[object]); } for (id object in keys) { NSLog(@"%@",dictionary1[object]); }

NSMutableDictionary

NSMutableDictionary *mutableDic = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"one",@"1",@"two",@"2", nil]; //增:添加没有顺序 [mutableDic setObject:@"three" forKey:@"3"]; //删 [mutableDic removeObjectForKey:@"2"]; //查 [mutableDic objectForKey:@"3"]; //改(根据key将原来的覆盖掉) //setobject...forkey方法，如果字典中没有添加的这个Key,就做添加处理，如果有，当修改处理 // 字典数组嵌套 NSArray *dataArr = @[@"a",@[@"ada",@"anie"], @{@"book":@[@"math",@"english",@"chinese"] } ]; NSLog(@"chinese:%@",[[[dataArr objectAtIndex:2] objectForKey:@"book"] objectAtIndex:2]); // dataArr[2][@"book"][2] NSLog(@"%@",dataArr[1][1]);