Problems extracting values from NSMutableArray - objective-c

Question

I'm trying to parse data from a plist file into a NSMutableArray.
In my plist
Root is a Dictionary containing an Array of 6 Numbers
I've created a label hooked with the IBOutlet UILabel *lbl4 object and I want this label to show the first element of the array made reading the plist. The problem is that the program crashes at the assigning instruction (the last one).
My code is this:
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docPath = [paths objectAtIndex:0];
NSString *plistPath = [docPath stringByAppendingPathComponent:#"settings.plist"];
if(![[NSFileManager defaultManager] fileExistsAtPath:plistPath]);
{
plistPath = [[NSBundle mainBundle] pathForResource:#"settings" ofType:#"plist"];
}
NSData *plistXML = [[NSFileManager defaultManager] contentsAtPath:plistPath];
NSString *err = nil;
NSPropertyListFormat format;
NSDictionary *temp = (NSDictionary *) [NSPropertyListSerialization propertyListFromData:plistXML mutabilityOption:NSPropertyListMutableContainersAndLeaves format:&format errorDescription:&err];
if(!temp)
{
NSLog(#"Error reading plist: %#, format: %d", err, format);
}
self.dataSet = [NSMutableArray arrayWithArray:[temp objectForKey:#"Dadi"]];
[lbl4 setText:[NSString stringWithFormat:#"%#", [dataSet objectAtIndex:0]]];
The plist source code is the following:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>Dadi</key>
<array/>
<key>D4</key>
<integer>0</integer>
<key>D6</key>
<integer>0</integer>
<key>D8</key>
<integer>0</integer>
<key>D10</key>
<integer>0</integer>
<key>D12</key>
<integer>0</integer>
<key>D20</key>
<integer>0</integer>
</dict>
</plist>
The Debug output says "2012-09-02 18:29:55.483 Faith[6014:707] * Terminating app due to uncaught exception 'NSRangeException', reason: '* -[__NSArrayM objectAtIndex:]: index 0 beyond bounds for empty array'"

Answer 1

In your plist, the array stored at the dictionary's Dadi key is empty!
<key>Dadi</key>
<array/>
So
self.dataSet = [NSMutableArray arrayWithArray:[temp objectForKey:#"Dadi"]];
Sets self.dataSet to an empty array (i.e. even index:0 is beyond the bounds).
I would check for se.f.dataSet.count == 0 and provide a default in this case.
#warrenm mentioned in the comments that the structure of your plist is not what you might have expected. These are XML files, so any tag which ends with /> is "self-closing", and therefore always empty. To contain those numbers, you need to add an ending tag and place them inside:
<array>
<integer>7</integer>
</array>
Of course, on further evaluation, your existing plist has keys associated with those, so this is possibly also not the right solution. You'll need to evaluate what your needs are for that plist.