How to view contents of NSDictionary variable in Xcode debugger?

Question

Is there a way to view the key/value pairs of a NSDictionary variable through the Xcode debugger? Here's the extent of information when it is fully expanded in the variable window:

Variable  Value      Summary
jsonDict  0x45c540   4 key/value pairs
 NSObject {...}
  isa     0xa06e0720

I was expecting it to show me each element of the dictionary (similar to an array variable).

Answer 1

In the gdb window you can use po to inspect the object.

given:

NSMutableDictionary* dict = [[NSMutableDictionary alloc] init];
[dict setObject:@"foo" forKey:@"bar"];
[dict setObject:@"fiz" forKey:@"buz"];

setting a breakpoint after the objects are added you can inspect what is in the dictionary

(gdb) po dict
{
  bar = foo;
  buz = fiz;
}

Of course these are NSString objects that print nicely. YMMV with other complex objects.

Answer 2

You can right-click any object (ObjC or Core Foundation) variable and select “Print Description to Console” (also in Run->Variables View). This prints the result the obejct’s -debugDescription method, which by default calls -description. Unfortunately, NSDictionary overrides this to produce a bunch of internal data the you generally don’t care about, so in this specific case craigb’s solution is better.

The displayed keys and values also use -description, so if you want useful information about your objects in collections and elsewhere, overriding -description is a must. I generally implement it along these lines, to match the format of the default NSObject implementation:

-(NSString *) description
{
    return [NSString stringWithFormat:@"<%@ %p>{foo: %@}", [self class], self, [self foo]];
}