如何解析JSON并拥有2个最终数据数组

Question

I am parsing an itunes rss feed with JSON but I have run into a problem. The following code is running properly for one the movieName output but I still don't get the movieSummary output.

-(void)connectionDidFinishLoading:(NSURLConnection *)connection {

    allDataDictionary = [NSJSONSerialization JSONObjectWithData:webData options:0 error:nil];
    feed = [allDataDictionary objectForKey:@"feed"];
    arrayOfEntry = [feed objectForKey:@"entry"];

    for (NSDictionary *dictionTitle in arrayOfEntry) {

        NSDictionary *title = [dictionTitle objectForKey:@"title"];
        NSString *labelTitle = [title objectForKey:@"label"];

        [arrayLable addObject:labelTitle];

        NSDictionary *summary = [dictionTitle objectForKey:@"summary"];
        NSString *labelSummary = [summary objectForKey:@"label"];

        [arraySummary addObject:labelSummary];
    }

    movieName.text = [arrayLable objectAtIndex:0];
    movieSummary.text = [arraySummary objectAtIndex:0]; //This is not displaying 
}

Here is the link that I am parsing: http://itunes.apple.com/us/rss/topmovies/limit=300/json

Answer 1

The problem was that when I was adding the strings to the Array that it sometimes contained NULL's thus the following code helped me out

    if ([[arrayName objectAtIndex:0] isKindOfClass:[NSNull class]]) {
    labelName.text = @"This is NULL";
} else {
    [arrayName addObject:labelName];
}

    if ([[arraySummary objectAtIndex:0] isKindOfClass:[NSNull class]]) {
    labelSummary.text = @"This is NULL";
} else {
    [arraySummary addObject:labelSummary];
}

Answer 2

I run into this situation a lot. I use something like this. Replace your code

NSString *labelTitle = [title objectForKey:@"label"];
[arrayLable addObject:labelTitle];

with

NSString * labelTitle = [ [ title objectForKey:@"label" ] ifNullThenNil ] ;
[ arrayLabel addObject:labelTitle ? labelTitle : @"" ] ; // you could also use @"<unknown>" or similar instead of @""

where -ifNullThenNil is provided via category:

@implementation NSObject (IfNullThenNil)
-(id)ifNullThenNil { return self ; }
@end

@implementation NSNull (IfNullThenNil)
-(id)ifNullThenNil { return nil ; }
@end