网站设计建设平台/小学生简短小新闻十条

NSDictionary的所有方法//什么是字典//字典是有索引的，每一个索引都对应一个内容//       key                    value//OC字典的核心就是key&value//NSDictionary NSMutableDictionary//NSDictionary//字典是无序的//alloc 创建NSDictionary *dic = [[NSDictionary alloc] initWithObjectsAndKeys:@"V1",@"K1", nil];//字典都是由一对对象组成的，这一对对象前者是value，后者是key,key是字符串,value是任意对象NSLog(@"%@",dic);//打印出来的字典由{}包围，{}里面是key = value的格式NSDictionary *dic1 = [[NSDictionary alloc] initWithDictionary:dic];//类方法 创建 key不要重复NSDictionary *dic2 = [NSDictionary dictionaryWithObjectsAndKeys:@"虾条",@"零食",@"面条",@"主食",@"手抓肉",@"炒菜",@"二锅头",@"饮料", nil];NSDictionary *dic3 = [NSDictionary dictionaryWithDictionary:dic2];//找到对应key的value//关键词是objectForKey：参数是key，返回值是对应key的value，value是什么类型的对象，返回值就是什么类型的返回值NSString *mainFood = [dic2 objectForKey:@"主食"];NSLog(@"%@",mainFood);NSString *drink = [dic2 objectForKey:@"饮料"];//遍历,遍历数组直接就遍历那些对象。字典遍历的时候不是value，遍历的是keyNSArray *dicArr = [dic2 allKeys];//通过allKeys可以找到一个字典里面的所有的key，返回值是一个数组for(int i = 0;i<[dicArr count];i++){NSLog(@"%@",[dicArr objectAtIndex:i]);}//练习，有一个字典@[@"a":@"A",@"b":@"B",@"c":@"C",@"d":@"D"]//先创建出来，//找到c这个key对应的value//遍历这个字典，查找是否有d这个key，如果有，打印他的valueNSDictionary *charDic = [NSDictionary dictionaryWithObjectsAndKeys:@"A",@"a",@"B",@"b",@"C",@"c",@"D",@"d", nil];NSLog(@"%@",[charDic objectForKey:@"c"]);NSArray *charDicArr = [charDic allKeys];for(NSString *tempStr in charDicArr){if([tempStr isEqualTo:@"d"]){NSLog(@"%@",[charDic objectForKey:tempStr]);}else{NSLog(@"这个不是");}}4、NSMutableDictionary的所有方法//NSMutableDictionary//创建NSMutableDictionary *mutableDic = [NSMutableDictionary dictionaryWithCapacity:0];//增添加新的key和value[mutableDic setValue:@"china" forKey:@"country"];[mutableDic setValue:@"北京" forKey:@"province"];//删除[mutableDic removeObjectForKey:@"country"];[mutableDic removeAllObjects];//练习//建一个可变字典NSMutableDictionary *peopleDic = [NSMutableDictionary dictionaryWithCapacity:0];//set两个value&key（name:lucy,age:16）[peopleDic setObject:@"lucy" forKey:@"name"];[peopleDic setObject:@"16" forKey:@"age"];//根据age找到valueNSLog(@"%@",[peopleDic objectForKey:@"age"]);//添加一个value&key(sex:female)[peopleDic setObject:@"female" forKey:@"sex"];//删除一个value&key(name)[peopleDic removeObjectForKey:@"name"];//全删[peopleDic removeAllObjects];//数组、字典里面的内容不光是字符串（NSString），而可能是所有的对象类型NSMutableArray *tableArr = [NSMutableArray arrayWithCapacity:0];for(int i = 0;i<5;i++){NSDictionary *hereDic = [NSDictionary dictionaryWithObjectsAndKeys:[NSString stringWithFormat:@"age is %d",arc4random()%100],@"age",[NSString stringWithFormat:@"sex is %d",arc4random()%1],@"sex",[NSString stringWithFormat:@"height is %d",arc4random()%200],@"height", nil];[tableArr addObject:hereDic];}NSLog(@"%@",tableArr);NSLog(@"age is %@",[[tableArr objectAtIndex:1] objectForKey:@"age"]);}