OC总结之字典

// 1.创建字典        NSDictionary *jack = [[NSDictionary alloc] initWithObjectsAndKeys:                              @"jack", @"name", @"18", @"age", nil];                // 2.快速创建字典，比较常用        NSDictionary *jack1 = @{                                @"name":@"jack",                                @"age":@"18"                                };        NSLog(@"%p %p",jack,jack1);        NSLog(@"jack = %@ jack1 = %@",jack,jack1);                NSNumber *number = [NSNumber numberWithInt:21];        NSArray *array = @[@"one",@"two",@"three"];                // 3.在字典中存储数据时没有顺序        NSDictionary *dic = @{                              @"array":array,                              @"number":number,                              @"dic":jack1                              };        NSLog(@"dic = %@",dic);                // 4.获取字典长度        NSUInteger count = [dic count];        NSLog(@"字典长度为 = %lu",count);                        // 5.从字典中取值//        Returns the value associated with a given key.//        返回键对应的值        NSArray *arrayInDic = [dic objectForKey:@"array"];        NSLog(@"字典中的array = %@",arrayInDic);                NSDictionary *dicInDic = [dic objectForKey:@"dic"];        NSLog(@"字典中的dic = %@",dicInDic);                NSNumber *numberInDic = [dic objectForKey:@"number"];        NSLog(@"字典中的number = %@",numberInDic);        // 1.快速创建的字典和数组都是不可变的        // 值，键，值，键...        NSMutableDictionary *mutableDic = [[NSMutableDictionary alloc]initWithObjectsAndKeys:@"jack",@"name",@"18",@"age", nil];        NSLog(@"mutableDic = %@",mutableDic);                // 2.如何向字典中'插入'一个数据                Person *person = [[Person alloc]init];        NSString *string = [[NSString alloc]initWithFormat:@"18"];//        - (void)setObject:(id)anObject forKey:(id <NSCopying>)aKey;        [mutableDic setObject:person forKey:@"height"];        NSLog(@"count = %ld",[person retainCount]);// strong reference 就要释放掉        [person release];        //        [string release];        NSLog(@"mutableDic = %@",mutableDic);        //        The value for aKey. A strong reference to the object is maintained by the dictionary. Raises an NSInvalidArgumentException if anObject is nil.// 键对应值，字典会强引用这个对象，        // 3.删除        [mutableDic removeObjectForKey:@"name"];        NSLog(@"%@",mutableDic);//        // 4.全部删除//        [mutableDic removeAllObjects];//        NSLog(@"mutableDic = %@",mutableDic);                // 5.遍历字典        // 获取字典中所有的键       NSArray *keysArray =  [mutableDic allKeys];        // 获取字典中所有的值        NSArray *valuesArray = [mutableDic allValues];//        Returns a new array containing the dictionary’s values.//The order of the values in the array isn’t defined.        // 返回包含字典中值的新数组  数组中值的顺序没有被定义        for (id key in keysArray) {            NSLog(@"key = %@",key);            id value = mutableDic[key]; // 获取某个key的值            NSLog(@"value = %@",value);        }                //