Question

I have an NSString.

NSString *str;

And I need to store it in a struct.

struct {
  int *s;
} st;

And set it.

st.s = str;

So, how should I go about retrieving it?

return (__bridge_retained NSString *)st.s;

I’ve tried the above, and it gives the error: Incompatible types casting ‘int *’ to ‘NSString *’ with a __bridge_retained cast.

---

Answered the question. Simply define the NSString in the struct like this.

struct {
  __unsafe_unretained NSString *s;
} st;

Thanks, Carl Veazey!

Answer 1

To store an Objective-C object in an struct you have a couple of options, the one I see most is to store it in the struct as __unsafe_unretained and then maintain a strong reference to it elsewhere.

From the “Common Issues While Converting a Project” section of the ARC Transition Notes:

If using Objective-C objects is sub-optimal, (maybe you want a dense
array of these structs) then consider using a void* instead. This
requires the use of the explicit casts…

They seem to imply __bridge is the way to cast void * to id but are not 100% clear on this.

The other option, which makes more sense to me personally and I’ve seen more often I think:

Mark the object reference as __unsafe_unretained. … You declare the
structure as: struct x { NSString * __unsafe_unretained S; int X; }

Hope this helps!