iOS: CFTypeRef disallowed with ARC

Question

I'd like get username/password out of my keychain. for this I followed this guide:

Simple iPhone Keychain Access

But this part is not allowed with ARC:

NSData *result = nil;    
OSStatus status = SecItemCopyMatching(
                  (CFDictionaryRef)searchDictionary,                                            
                  (CFTypeRef *)&result);

What can I do?

Hesitancy

Answer 1

ARC only manages Objective-C types. If you cast to Core Foundation types you have to tell ARC who owns the variable by using __bridge, __bridge_retained or __bridge_transfer.

Here's Apple's official documentation on toll-free bridging under ARC, or see this blog post (scroll down to Toll-Free Bridging) for a great overview.

For example:

NSData *inData = nil;
CFTypeRef inTypeRef = (__bridge CFTypeRef)inData;
OSStatus status = SecItemCopyMatching(
                   (__bridge CFDictionaryRef)searchDictionary, 
                   &inTypeRef);

Piacular

thank you simon. I already used __bridge but for (CFTypeRef *)&result); it didn't work.. Xcode noticed: Incompatible types casting 'NSData *__strong *' to 'CFTypeRef *' (aka 'const void **') with a __bridge cast – Hesitancy

Separate out your cast from your dereference. Something like this: CFTypeRef r = (__bridge CFTypeRef)result; OSStatus status = SecItemCopyMatching((__bridge CFDictionaryRef)searchDictionary, &r); – Piacular

didn't work. leelang solution for some reason did. xcode 7.3 – Loux

Answer 2

CFTypeRef inData = NULL;
OSStatus status = SecItemCopyMatching(
                   (__bridge CFDictionaryRef)searchDictionary, 
                   & inData);
NSData *data = (__bridge NSData *)inData;

Wordless

"Try this" is not very useful since it doesn't explain what was wrong of how to fix it in another case. – Ellerd