如何在方法中使用此值 - 目标C.

Question

I have to pass the following object to a method, have that method modify it so that after the method call I can move on with my modified object.

AVMutableCompositionTrack *compositionVideoTrack[2];

passing it like this currently:

[self buildShow:&compositionVideoTrack];

the buildshow method looks like this:

-(void)buildShow:(AVMutableCompositionTrack**)videoTracks{
}

I am getting this compiler warning and it is not currently working:

Incompatible pointer types sending 'AVMutableCompositionTrack *__strong (*)[2]' to parameter of type 'AVMutableCompositionTrack *__autoreleasing *'

How can I change this to make it work?

Answer 1

Just pass it like this:

[self buildShow:compositionVideoTrack];

When you declare it like this:

AVMutableCompositionTrack * __autoreleasing compositionVideoTrack[2];

It's already an array of pointers, so it's compatible with the type of the parameter ( AVMutableCompositionTrack** ).

Answer 2

Unless you're working with a property, you ought to do it like this (note that the method now returns the object of the same type):

method constructor:

-(AVMutableCompositionTrack *)buildShow:(AVMutableCompositionTrack *)videoTracks {
    // do something
    return newVideoTracks;
}

And, method call:

newVideoTracks = [self buildShow:compositionVideoTrack];

If you use a property, you can have a void method with no parameters.