Can we use inout parameters in a Objective-C block?

Asked Oct 01 '14 at 20:51

Active Oct 01 '14 at 20:51

Viewed 881 times

Something like this ?

^void (__unsafe_unretained UIViewController self, UIScrollView *scrollView, CGPoint velocity, inout CGPoint *targetContentOffset){
    // Something
}

or whats the alternative to using such paramrters.

Context:

I am trying to swizzle the scrollViewWillEndDragging:withVelocity:targetContentOffset: method of the UIScrollviewDelegate but the last parameter targetContentOffset is an inout parameter. I am using https://github.com/JonasGessner/JGMethodSwizzler to swizzle the instances which expects a block to be used as a replacement method.

Code which I am trying to use...

[scrollViewDelegateObj swizzleMethod:@selector(scrollViewWillEndDragging:withVelocity:targetContentOffset:) withReplacement:^id(JG_IMP original, __unsafe_unretained Class swizzledClass, SEL selector) {
        return JGMethodReplacement(void, UIViewController *, UIScrollView *scrollView, CGPoint velocity, CGPoint *targetContentOffset){
            JGOriginalImplementation(void, scrollView, velocity, targetContentOffset);

    };
}];

Can anyone help me out ?

asked Oct 01 '14 at 20:51

mohkhan

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Yes, you can: Cocoa's collection classes have enumeration methods taking Blocks with such parameters. Does your code not work? – jscs Oct 01 '14 at 20:53
No, I get a compile time error – mohkhan Oct 01 '14 at 20:53
And what is that error? – jscs Oct 01 '14 at 20:53
Unknown type name 'inout' :( – mohkhan Oct 01 '14 at 20:54
What happens if you remove the word `inout`? – jscs Oct 01 '14 at 20:54
The library compares the original method signature with the signature of the block and only goesahead with swizzling if they match. In this case the library expects 'N^{CGPoint=dd}' for the orignal mathod bu the block signature is '{CGPoint=dd}' which do not match and the swizzling fails. – mohkhan Oct 01 '14 at 20:57
I see...let me look into this. – jscs Oct 01 '14 at 21:01
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/62292/discussion-between-mohkhan-and-josh-caswell). – mohkhan Oct 01 '14 at 21:05

Can we use inout parameters in a Objective-C block?

0 Answers0