Parsing JSON data and handling an Array

Question

I am using Mantle to parse some JSON data from Yelp.

For each business returned I get an NSArray of categories. This would be an example:

yelpCategories =     (
            (
        "Wine Bars",
        "wine_bars"
    ),
            (
        "Ice Cream & Frozen Yogurt",
        icecream
    )
);

yelpCategories is the name of the array that I save. Later on I am trying to parse the array into a string:

    NSMutableString *yelpCats = [[NSMutableString alloc] init];
    for (NSObject * obj in business.yelpCategories)
    {
        [yelpCats appendString:[NSString stringWithFormat:@"%@,",[obj description]]];
    }

The issue is with the above. I am being returned a string just as "(" so I must be accessing the array incorrectly. How can I correctly access each object, ideally I would be looking for the end string o be @"Wine Bars, Ice Cream & Frozen Yogurt".

EDIT

The categories array: (
        (
        Pubs,
        pubs
    )
)

FINAL EDIT - Proposed Solution

for (NSArray *cats in business.yelpCategories)
{
    NSString *category = [cats objectAtIndex:0];
    if ([category length] > 0) {
        category = [category substringToIndex:[category length] - 1];
    }

    if (cats == business.yelpCategories.lastObject) {
        [yelpCats appendString:[NSString stringWithFormat:@"%@",category]];
    } else {
        [yelpCats appendString:[NSString stringWithFormat:@"%@, ",category]];
    }
}
cell.yelpCategories.text = yelpCats;

i_am_jorf · Accepted Answer · 2014-05-03 15:50:59Z

2

Using the description of the object gives you what you see in the debugger, which includes extra carriage returns.

What you want to do is something like:

yelpCats = [yelpCategories componentsJoinedByString:@", "];

answered May 3, 2014 at 15:50

i_am_jorf

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2 Comments

StuartM Over a year ago

I still get the same output of '(' with the above approach... Is this because of how the data is stored it looks like an array in an array?

StuartM Over a year ago

Added a final edit with the proposed solution which works, but I thought I would share in the question to determine if there was a better approach than submitting as the answer, please let me know. Thanks

Brandon · Accepted Answer · 2014-05-03 16:19:41Z

1

@jeffamaphone 's answer is the correct and best way of doing things however what your doing will almost work, I think your just confused on the contents of the array.

The yelpCategories array is an array of strings so you don't need to call stringWithFormat or call the description method. In fact [obj description] will return a string so you didn't even need stringWithFormat in your example and you would have gotten the same output. To make your original method work change to:

NSMutableString *yelpCats = [[NSMutableString alloc] init];
for (id obj in business.yelpCategories)
{
    //obj is a string so we can just append it.
    [yelpCats appendString:obj]];
}

Also noticed I changed NSObject *obj to just id obj, this is the idiomatic way and shorthand way of declaring NSObjects in objective-c. In this example however I would actually use (NSString *category in business.yelpCategories) instead for better readability. In this case you are declaring to everyone that you expect each object in the array to be a string and then if you wanted to use NSString methods on it inside the loop then you don't have to cast it.

answered May 3, 2014 at 16:19

Brandon

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6 Comments

StuartM Over a year ago

I get an error with both of your suggested approaches: NSInvalidArgumentException', reason: '-[__NSCFArray length]: unrecognized selector sent to instance

Brandon Over a year ago

I made the assumption that the business.yelpCategories array held strings which it seems like it doesn't. Can you provide the json your trying to parse and the contents of your array? You can do an NSLog(@"Array contents: %@", business.yelpCategories) to see the contents.

StuartM Over a year ago

I did originally to the question, but have an added an EDIT to be clear. That log is the business.yelpCategories array

StuartM Over a year ago

Also note how the data is set out i.e. ("Pubs", "pubs") I would looking to only catch Pubs the first entry in that case

StuartM Over a year ago

Added a final edit with the proposed solution which works, but I thought I would share in the question to determine if there was a better approach than submitting as the answer, please let me know. Thanks

|

StuartM · Accepted Answer · 2014-05-06 16:42:25Z

0

for (NSArray *cats in business.yelpCategories)
{
    NSString *category = [cats objectAtIndex:0];
    if ([category length] > 0) {
        category = [category substringToIndex:[category length] - 1];
    }

    if (cats == business.yelpCategories.lastObject) {
        [yelpCats appendString:[NSString stringWithFormat:@"%@",category]];
    } else {
        [yelpCats appendString:[NSString stringWithFormat:@"%@, ",category]];
    }
}
cell.yelpCategories.text = yelpCats;

answered May 6, 2014 at 16:42

StuartM

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