why not creat a method signature directly to return?

[nicklockwood]

why not creat a method signature directly to return?

[nicklockwood]

What about the return type? If the expected return type is a struct (> 8 bytes), and you return an integer, couldn't that corrupt the stack?

[nicklockwood]

I think this is also a problem in the more common case where the return type is a float or double, because floating point values are returned in a different register than integers/pointers.

[ireland2011]

thank you

[desperadocarl]

I am still confused , if i change the NSMethodSignature , is the expected MethodReturnType not already changed?

I did what @ireland2011 said
invocation's return value is already Q(integer)
where is expected return type? expected return type not depends on new NSMethodSignature?

Code：
NSDate * nullDic = [NSNull null];
[nullDic earlierDate:[NSDate date]];

• (NSMethodSignature *)methodSignatureForSelector:(SEL)selector
  {
  //look up method signature
  NSMethodSignature *signature = [super methodSignatureForSelector:selector];
  NSString *str = @"123"; NSMethodSignature *sign = [str methodSignatureForSelector:@selector(length)];
  sign.methodReturnType;

  return sign;
  }

• (void)forwardInvocation:(NSInvocation *)invocation
  {
  invocation.target = nil;
  invocation.selector = @selector(length);
  [invocation invoke];
  }

<NSInvocation: 0x6040000701c0>
return value: {Q} 0
target: {@} 0x0
selector: {:} length