How to maintain order when converting jsonstring to NSDictionary using NSJSONSerialization

Question

Created Apr ’24

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    NSString *jsonString = @"{\"key1\":\"value1\",\"key2\":\"value2\",\"key3\":\"value3\",\"key4\":\"value4\"}";
    NSString *jsonString2 = @"{\"key2\":\"value2\",\"key1\":\"value1\",\"key4\":\"value4\",\"key3\":\"value3\"}";
    NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
    NSData *jsonData2 = [jsonString2 dataUsingEncoding:NSUTF8StringEncoding];
    NSDictionary *dict1 = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableContainers error:nil];
    NSDictionary *dict2 = [NSJSONSerialization JSONObjectWithData:jsonData2 options:NSJSONReadingMutableContainers error:nil];

iShot_2024-04-28_11.11.56.png

The expected results are：

dict1:key1,key2,key3,key4
dict2:key2,key1,key4,key3

Is there any way to make that happen?

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Answer 1

galad87 OP

Apr ’24

NSDictionary doesn't make any guarantee about order, it's a data structure that is not meant to be ordered, so it's not a surprise the result looks like that. There is a NSJSONWritingSortedKeys option if you want things in lexicographic order when converting from NSObjects to json. If not you will have to use an NSArray.

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