How do I get values from a tiered .plist?

Question

I've already looked at Parse Plist (NSString) into NSDictionary and deemed it to be not a duplicate, as that question and its answer do not address my concerns.

---

I have a .plist file in the file system structured like this:

The source code of this .plist file looks like this:

{
    "My App" = {
        "Side Panel" = {
            Items = {
                Price = "#123ABC";
            };
        };
    };
}

I know how to get an item in the Root like this:

[[NSBundle mainBundle] pathForResource:@"filename" ofType:@"plist"];
NSDictionary *dict = [NSDictionary dictionaryWithContentsOfFile:path];
NSString value = [dict objectForKey:@"key"]);

But what if the structure is like mine, with tiered dictionaries? How do I get the value of Price?

I would like to do this all in one method, ideally like this:

Calling

NSString *hexString = [self getColorForKey:@"My App.Side Panel.Items.Price"];

Definition

- (NSString *) getColorForKey: (NSString *)key
{
    NSArray *path = [key componentsSeparatedByString:@"."];
    NSDictionary *colors = [NSDictionary dictionaryWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"Colors" ofType:@"plist"]];
    NSString *color = @"#FFFFFF"; // white is our backup

    // What do I put here to get the color?

    return color;
}

Answer 1

Here's the solution that worked for me:

+ (NSString*) getHexColorForKey:(NSString*)key
{
    NSArray *path = [key componentsSeparatedByString:@"."];
    NSDictionary *colors = [NSDictionary dictionaryWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"Colors" ofType:@"plist"]];
    NSString *color = @"#FFFFFF";
    for (NSString *location in path) {
        NSObject *subdict = colors[location];
        if ([subdict isKindOfClass:[NSString class]])
        {
            color = (NSString*)subdict;
            break;
        }
        else if ([subdict isKindOfClass:[NSDictionary class]])
        {
            colors = (NSDictionary*)subdict; // if it's a dictinoary, our color may be inside it
        }
        else
        {
            [SilverLog level:SilverLogLevelError message:@"Unexpected type of dictinoary entry: %@", [subdict class]];
            return color;
        }
    }
    return color;
}

where key is an NSString that matches /^[^.]+(\.[^.]+)*$/, meaning it looks like my targeted @"My App.Side Panel.Items.Price".

Answer 2

Yes I understand what you're looking to accomplish; thank you for the clarification. I will however add that the resources and advice I have written do provide the necessary information resolve your problem.

That said, the following gets your dictionary:

NSURL *plistURL = [[NSBundle mainBundle] URLForResource:@"Info" withExtension:@"plist"];
NSData *plistData = [NSData dataWithContentsOfURL:plistURL];
NSDictionary *tieredPlistData = [NSPropertyListSerialization propertyListWithData:plistData 
                                                                          options:kCFPropertyListImmutable 
                                                                           format:NULL 
                                                                            error:nil];

Then, if we're interested in the information contained in Items

NSDictionary *allItemsDictionary = tieredPlistData[@"My App"][@"Side Panel"][@"Items"];

Assuming that Items will contain a number of objects, you could use

NSArray *keys = [allItems allKeys];
for(NSString *key in keys){
    NSString *colorValue = allItemsDictionary[key];
    // do something with said color value and key
}

Or, if there is a single value you need, then just reference that key

NSString *colorForPriceText = allItemsDictionary[@"Price"];

But a few tips:

• It's generally considered a better idea to keep frequently accessed values in code instead of a plist/file that is loaded at runtime.
• That said, you wouldn't put your call to load from NSBundle in the same method you would use to query a specific value. In your example, every time you need a color, you end up re-accessing NSBundle and pile on unneeded memory allocations. One method would load the plist into an iVar NSDictionary and then that NSDictionary would be used separately by another method.