CODEWITHSUNDEEP
objective-cxcodensdictionarynsmutabledictionarynslog
Nikita
Nikita

Reputation: 327

Value for key from NSMutableDictionary doesn't print

I'm learning "Programming in Objective-C" from Stephen Kochan and I have a problem with a mutable copy of NSDictionary. So, here is my code:

NSMutableString *value1 = [[NSMutableString alloc ] initWithString: @"Value for Key one" ];
    NSMutableString *value2 = [[NSMutableString alloc ] initWithString: @"Value for Key two" ];
    NSMutableString *value3 = [[NSMutableString alloc ] initWithString: @"Value for Key three" ];
    NSMutableString *value4 = [[NSMutableString alloc ] initWithString: @"Value for Key four" ];
    NSString *key1 = @"key1";
    NSString *key2 = @"key2";
    NSString *key3 = @"key3";
    NSString *key4 = @"key4";

    NSDictionary *dictionary = [[NSDictionary alloc] initWithObjectsAndKeys: value1, key1, value2, key2, value3, key3, nil];

    NSDictionary *dictionaryCopy = [[NSDictionary alloc] init];
    NSMutableDictionary *dictionaryMutableCopy = [[NSMutableDictionary alloc] init];

    dictionaryCopy = [dictionary copy];
    dictionaryMutableCopy = [dictionary mutableCopy];

    [value1 setString: @"New value for Key one" ];
    [value2 setString: @"New value for Key two" ];
    [value3 setString: @"New value for Key three" ];

    dictionaryMutableCopy[key4] = value4;

    NSLog(@"All key for value 4");

    for (NSValue *key in [dictionaryMutableCopy allKeysForObject:value4]) {
        NSLog(@"key: %@", key);
    }

    NSLog(@"All values");

    for (NSValue *val in [dictionaryMutableCopy allValues]) {
        NSLog(@"value: %@", val);
    }

    for (NSValue *key in [dictionaryMutableCopy allKeys]) {
        NSLog(@"Key: %@ value: %@", key, dictionary[key]);
    }

How you see and the end of the code I'm printing all key/values from my NSMutableDictionary, but for key 4 I haven't a value!

Screen from terminal

But how you can see the value for key 4 is't null!

[Content of NSMutableDictionary][2]

What's the problem? Please help

Upvotes: 1

Views: 345

Answers (1)

trojanfoe
trojanfoe

Reputation: 122381

In the final for loop, you are getting the value from dictionary instead of dictionaryMutableCopy:

for (NSValue *key in [dictionaryMutableCopy allKeys]) {
    NSLog(@"Key: %@ value: %@", key, dictionaryMutableCopy[key]);
    //                               ^^^^^^^^^^^^^^^^^^^^^
}

Upvotes: 2

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