Re: Mixing Obj-C and C "methods"
Re: Mixing Obj-C and C "methods"
- Subject: Re: Mixing Obj-C and C "methods"
- From: Vincent Habchi <email@hidden>
- Date: Tue, 30 Jul 2013 10:27:34 +0200
Rick,
thanks for answering, because what I found on the Internet seems contradictory. Some say that if the C function is placed inside the implementation block, then it can access attributes as if it were a true Obj-C method; some say otherwise. So it’s a bit difficult to find a definitive answer thereon.
> Having said that, most callback APIs allow you to pass a context parameter that gets passed back to your C callback. Often times, this context parameter is a void* you pass in along with a pointer to your callback function. You can pass "self" in this parameter when you register the callback, then cast it inside your callback back to MyClass* (or whatever your class is).
Yes, right; it’s a SQLite callback, the first parameter is a void *. I wanted to pass a pointer to a structure containing both a unique query id (out of uuid) and a pointer to self, but got told off by ARC because it apparently forbids to embed pointers to Obj-C objects in C-structs. So I just bridge-cast it to void *.
Assuming the pointer to the struct is named ‘info’ and the field containing a reference to ‘self’ is called ‘this’, [info->this someMethod] as well as info->this->someAttribute are legal, aren’t they?
Thanks a lot!
Vincent
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