How to reconstruct NSAttributedString from JSON data

Question

I have this NSAttributedString object that I have managed to write in a file like this:

{
  "string" : "Hello World",
  "runs" : [
    {
      "range" : [0,3],
      "attributes" : {
        "font" : {
          "name" : "Arial",
          "size" : 12
        }
      }
    },
    {
      "range" : [3,6],
      "attributes" : {
        "font" : {
          "name" : "Arial",
          "size" : 12
        },
        "color" : [255,0,0]
      }
    },
    {
      "range" : [9,2],
      "attributes" : {
        "font" : {
          "name" : "Arial",
          "size" : 12
        }
      }
    }
  ]
}

Now I have to read the data back and reconstruct the NSAttributedString
any ideas?

Answer 1

Deserialize your JSON string to get a dictionary with values. Then parse out the bits as you need them.

First parse out the string:

NSString *myString = [dictionaryFromJson objectForKey:@"string"];
NSMutableAttributedString *myAttributedString = [[NSMutableAttributedString alloc] initWithString:myString];

Then parse out the array:

NSArray *attributes = [dictionaryFromJson objectForKey:@"runs"];

Then traverse the array and for each dictionary in it, create the attributes as needed:

for(NSDictionary *dict in attributes)
{
    NSArray *rangeArray = [dict objectForKey:@"range"];
    NSRange range = NSMakeRange([(NSNumber*)[rangeArray objectAtIndex:0] intValue], [(NSNumber*)[rangeArray objectAtIndex:0] intValue]); //you may need to make sure here your types in array match up and of course that you are in bounds of array

    NSDictionary *attributesDictionary = [dict objectForKey:@"attributes"];

    //I'll do the font as example
    NSDictionary *fontDictionary = [attributesDictionary objectForKey:@"font"];
    if(fontDictionary)
    {
        NSString *fontName = [fontDictionary objectForKey:@"name"];
        float fontSize = [[fontDictionary objectForKey:@"size"] floatValue];
        UIFont *myFont = [UIFont fontWithName:fontName size:fontSize];

        if(myFont)
        {
             [myAttributedString addAttribute:NSFontAttributeName value:myFont range:range];
        }
    }
}

Then just carry on with the rest of the values, manipulating data based on whether they come from dictionaries or arrays.

You will also need to do some validation, null-checks etc., so this code is by no means complete.