ios – NSInvocation和内存问题

参见英文答案 > NSInvocation getReturnValue: called inside forwardInvocation: makes the returned object call dealloc:3个
所以我来自Java世界,我们对内存管理问题一无所知.在大多数情况下,ARC已经救了我的屁股,但这里有些让我难过的东西.基本上我使用NSInvocations来处理一些事情,在进行以下代码修改之前,我遇到了一些讨厌的内存问题.由于我做了这些修改,内存崩溃已经消失,但我通常非常害怕我不理解的代码.我这样做了吗？

之前：各种内存问题：

NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:[[target class] instanceMethodSignatureForSelector:selector]];
[invocation setSelector:selector];
[invocation setTarget:target];
[invocation setArgument:&data atIndex:2];
[invocation setArgument:&arg atIndex:3];
[invocation invoke];

Nsstring *returnValue;
[invocation getReturnValue:&returnValue];

之后：没有内存问题,但我不确定我是否正确：

NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:[[target class] instanceMethodSignatureForSelector:selector]];
[invocation setSelector:selector];
[invocation setTarget:target];
[invocation setArgument:&data atIndex:2];
[invocation setArgument:&arg atIndex:3];
[invocation invoke];

CFTypeRef result;
[invocation getReturnValue:&result];

if (result)
    CFRetain(result);

Nsstring *returnValue = (__bridge_transfer Nsstring *)result;

编辑：

我只想根据下面的答案添加,我使用了objc_msgSend,因此：

Nsstring * returnValue = objc_msgSend(target,selector,data,arg);

它解决了所有内存问题,而且看起来更简单.如果您发现此问题,请发表评论.

[target performSelector:selector withObject:data withObject:args];

id returnValue = objc_msgSend(target,/* argument1,argument2,... */);

// Cast the objc_msgSend function to a function named BOOLMsgSend which takes one argument and has a return type of BOOL.
BOOL (*BOOLMsgSend)(id,SEL,id) = (typeof(BOOLMsgSend)) objc_msgSend;
BOOL ret = BOOLMsgSend(target,arg1);

#import <objc/message.h>

@import ObjectiveC.message;