# getReturnValue: Gets the invocation’s return value. ``` - (void) getReturnValue:(void *) retLoc; ``` ## Parameters `retLoc` An untyped buffer into which the invocation copies its return value. It should be large enough to accommodate the value. See the discussion below for more information about `buffer`. ## Discussion Use the `NSMethodSignature` method [`methodReturnLength`](/documentation/Foundation/NSMethodSignature/methodReturnLength) to determine the size needed for `buffer`: ```objc NSUInteger length = [[myInvocation methodSignature] methodReturnLength]; buffer = (void *)malloc(length); [invocation getReturnValue:buffer]; ``` When the return value is an object, pass a pointer to the variable (or memory) into which [`NSInvocation`](/documentation/Foundation/NSInvocation) should place the object. In the following example, `myInvocation` represents a call to a no-argument method called `createReturnValue` in a class called `MyClass`, which returns an [`NSMutableString`](/documentation/Foundation/NSMutableString). The example performs the invocation with [`invoke`](/documentation/Foundation/NSInvocation/invoke), then retrieves the object with [`getReturnValue:`](/documentation/Foundation/NSInvocation/getReturnValue:) and copies it to a strongly-held property called `myObject`. > Warning: > ``doc://com.apple.foundation/documentation/Foundation/NSInvocation`` copies the return value directly into `buffer` without any memory bookkeeping, even when using Automatic Reference Counting (ARC). When using ARC, pass a pointer whose memory semantics match those expected by the method. Otherwise, an over-release crash may occur. For typical Objective-C methods, where ownership isn’t returned to the caller, use an `unsafe_unretained` variable. You can then copy this into another form of storage, like a strongly-held property. However, if the only thing keeping the returned value alive is the invocation’s ``doc://com.apple.foundation/documentation/Foundation/NSInvocation/target``, then you must keep the target alive while using the returned value. You can do this with the macro ``doc://com.apple.foundation/documentation/Foundation/NS_VALID_UNTIL_END_OF_SCOPE`` on the target. The following example shows how to properly manage memory when using ARC. ```objc // Create invocation, set selector, and invoke. NS_VALID_UNTIL_END_OF_SCOPE MyClass* myTarget = [[MyClass alloc] init]; NSMethodSignature* mySignature = [MyClass instanceMethodSignatureForSelector: @selector(createReturnValue)]; NSInvocation* myInvocation = [NSInvocation invocationWithMethodSignature: mySignature]; [myInvocation setSelector: @selector(createReturnValue)]; [myInvocation invokeWithTarget: myTarget]; // Retrieve return value and assign to property. __unsafe_unretained id tempObject = nil; [myInvocation getReturnValue: &tempObject]; self.myObject = tempObject; ``` If you haven’t invoked the [`NSInvocation`](/documentation/Foundation/NSInvocation) object, the result of this method is undefined. ## See Also [`@property (readonly) const char * methodReturnType;`](/documentation/Foundation/NSMethodSignature/methodReturnType) A C string encoding the return type of the method in Objective-C type encoding. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)