IOS 8: "Turn" corefoundation and nsobject transitions under ARC

Source Address: http://fann.im/blog/2013/12/25/corefoundation-bridge-nsobject/

Corefoundation has its own reference counting processing method, under CF if the method of generating the object has create, retain, copy means that CF will add one to the reference count in its own way, which needs to be released at the end CFRelease() . ARC currently only has an automatic reference count processing for NSObject objects, so the __bridge __bridge_transfer __bridge_retained conversion of reference count management is required in arc if there are corefoundation objects and NSObject object conversions.

• __bridgeRepresents a reference count balance for CF objects and nsobject, without the need to convert administrative rights. Suitable for converting CF objects obtained with a method that does not contain create, retain, copy to NSObject.
• __bridge_transferIndicates that the reference count administrator of the CF object is transferred to NSObject, which is managed by ARC, without any further CFRelease() release.
• __bridge_retainedIndicates that the reference count management of the NSObject object is transferred to CF management, and the reference count is added one, then the object needs to be disposed at the CF layer CFRelease() .

The SDK has two macros CFBridgingRetain that CFBridgingRelease can be used directly, to be aware of the CFBridgingRetain CFRelease() release.

After using a cfbridgingretain in an nsobject, the caller must take responsibility for calling Cfrelease at an APPROPRI Ate time.ns_inline cf_returns_retained cftyperef  Cfbridgingretain (id x) {return  (__bridge_retained cftyperef) span class= "n" >x;} ns_inline id cfbridgingrelease ( cftyperef cf_consumed x) {return  (__bridge_transfer id) x;}            

Refer to Arc engineering conversion and development considerations

IOS 8: "Turn" corefoundation and nsobject transitions under ARC