Question

So, having a hard time dereferencing some data I’ve loaded into arrays and dictionaries:

Inside a controller:

- (void)setupVendorsArray {
    self.vendorsArray = [NSArray arrayWithObjects:@"Toyota", @"Honda",nil];
}

- (void)setupProductFamiliesHash {

    NSArray *lowcost = [NSArray arrayWithObjects:@"Corolla", @"Fit",nil];
    NSArray *midrange = [NSArray arrayWithObjects:@"Camry", @"Accord",nil];
    NSArray *highend = [NSArray arrayWithObjects:@"Lexus", @"Acura",nil];
    NSArray *trucks = [NSArray arrayWithObjects:@"Tacoma", @"Ridgeline",nil];

    NSDictionary *lc = [NSDictionary dictionaryWithObjects:lowcost forKeys:self.vendorsArray]; 
    NSDictionary *mr = [NSDictionary dictionaryWithObjects:midrange forKeys:self.vendorsArray]; 
    NSDictionary *he = [NSDictionary dictionaryWithObjects:highend forKeys:self.vendorsArray]; 
    NSDictionary *tk = [NSDictionary dictionaryWithObjects:trucks forKeys:self.vendorsArray]; 

    self.productFamiliesHash = [NSArray arrayWithObjects:lc,mr,he,tk,nil];
}

In gdb print-object results in this for productFamiliesHash:

(gdb) print-object self.productFamiliesHash
<__NSArrayI 0x6b2c760>(
{
    Toyota = "Corolla";
    Honda = "Fit";
},
{
    Toyota = "Camry";
    Honda = "Accord";
},
{
    Toyota = "Lexus";
    Honda = "Acura";
},
{
    Toyota = "Tacoma";
    Honda = "Ridgeline";
}
)

But, for the life of me I can’t seem to access, for example, Toyota Corolla, which I would expect I could do like this in gdb:

(gdb) p [[productFamiliesHash objectAtIndex:0] objectForKey:@"Toyota"]

However, gdb gives:

Unable to call function "objc_msgSend" at 0x156408c: no return type information available.

How do I dereference the dictionary within the array?

Answer 1

Try using po instead of p. For Objective-C methods, p requires that you cast the result:

(gdb) p (id) [[productFamiliesHash objectAtIndex:0] objectForKey:@"Toyota"]

Even then, you won’t get the description of the object, only the pointer value.