Objective-C中的NSDictionary/NSMutableDictionary

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NSDictionary：字典，以key-value存储数据，存储的内存不是连续的，使用键值编码。

1.NSDictionary的声明

NSArray *arr_key = [NSArray arrayWithObjects:@"1", @"2", @"3", nil];

NSArray *arr_value = [NSArray arrayWithObjects:@"a",@"b",@"c",nil];

NSDictionary *dic = [NSDictionary dictionaryWithObjects:arr_value forKeys:arr_key];

NSLog(@"dic = %@", dic);

// NSDictionary的简单声明方式

NSDictionary *dic_s = @ { @"1":@"a", @"2":@"b", @"3":@"c" };

NSLog(@"dic_s = %@", dic_s);

2. NSDictionary的大小

int count = (int) [dic count];

3.取得NSDictionary的值

NSString *value = [ dic valueForKey:@"1" ]; // 取出key对应的值

NSString *vaule)1 = [ dic objectForKey:@"1" ];// 取出key对应的值

NSArray *array_key = [ dic allKeys ];// 取出NSDictionary中所有的key值，组成数组

NSArray *array_value = [ dic allValues ];// 取出NSDictionary中所有的value值，组成数组

// 匹配获得NSDictionary中部分key对应的value，如果找到对应的value，则返回value本身，若不存在，则返回notFoundMarker

NSArray *array = [dic objectsForKeys:[ NSArray arrayWithObjects:@"1", @"2", @"5",nil ] notFoundMarker:@"not found"];

4.NSDictionary遍历

for(NSString *keyin dic)

{

NSString *val = [dicobjectForKey:key];

NSLog(@"%@ = %@", key, val);

}

NSEnumerator *en = [dickeyEnumerator];//枚举器遍历NSDictionary

id key =nil;

while (key = [ennextObject])

{

id val = [ennextObject];

NSLog(@"%@ = %@", key,val);

}

5.NSMutableDictionary可变字典

NSMutableDictionary *dic_m = [[ NSMutableDictionary alloc ] init ] ;

5-1 给NSMutableDictionary添加key-value的数值

[dic_m setObject:@"a" forKey:@"1"]; //添加了key＝1，value＝a的数值

[dic_m setObject:@"b" forKey:@"2"];

5-2 删除键值对

[ dic_m removeAllObjects ]; // 删除NSMutableDictionary中所有的k-v数值

[ dic_m removeObjectForKey:@"2" ];// 删除NSMutableDictionary中key="1"的键值对

[ dic_m removeObjectsForKeys:[ NSArray arrayWithObjects:@"1", @"2", @"3", nil ] ] ;//删除多个key-value的键值对

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