Question

I have an NSDictionary and I am trying to pull a string out of it. For some reason, the last string seems irretrievable(!?!). In the code below, I retrieve the NSString object for labelString, with no problem at all. But when I try to retrieve the NSString for foo, I always get nil. But I don’t see the difference – can you see what I’m doing wrong?

NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:
                      [NSNumber numberWithInt:CellStyleLabelledStringCell], @"cellStyle",
                      @"name", @"fieldName", 
                      @"Name", @"labelString", 
                      foodItem.name, @"contentString", 
                      @"foo", @"fookey",
                      nil];

NSString *string1 = (NSString *)[dict objectForKey:@"fookey"];
NSString *string2 = (NSString *)[dict objectForKey:@"labelString"];
NSLog(@"[%@][%@]", string1, string2);

The log message looks like this, and backs-up what I’m seeing in the debugger (i.e., string1 is null):

2012-03-17 21:35:03.302 QuickList7[8244:fb03] [(null)][Name]

Truly perplexed. Thanks in advance.

Answer 1

foodItem.name is nil, so -[NSDictionary dictionaryWithObjectsAndKeys:] stops there, and doesn’t add the subsequent objects to the dictionary.

In other words, it’s as if you did this:

NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:
                      [NSNumber numberWithInt:CellStyleLabelledStringCell], @"cellStyle",
                      @"name", @"fieldName", 
                      @"Name", @"labelString", 
                      nil];

This is why you have to be careful with any method that takes nil as an “end of arguments” sentinel.