Passing an NSArray from Swift into Objective-C function

Question

I am calling a function from an Objective-C class. I passing an array from my Swift class into an Objective-C function.

Here is my code for the Swift

var videosAutoCompletion:[String] = []

completeSearch.autocompleteSegesstions(searchText, self.tableView, self.videosAutoCompletion)

Objective-C Function

 -(void)autocompleteSegesstions : (NSString *)searchWish :(UITableView*)table :(NSArray*)stringArray

Inside the Objective-C function i had a block

  dispatch_sync(dispatch_get_main_queue(), ^{
        self.ParsingArray = [[NSMutableArray alloc]init]; //array that contains the objects.
        for (int i=0; i != [jsonObject count]; i++) {
            for (int j=0; j != 1; j++) {
                //NSLog(@"%@", [[jsonObject objectAtIndex:i] objectAtIndex:j]);
                [self.ParsingArray addObject:[[jsonObject objectAtIndex:i] objectAtIndex:j]];
                //Parse the JSON here...
                //NSLog(@"Parsing Array - %@",self.ParsingArray);

                stringArray =  [self.ParsingArray copy];
                [table reloadData];

            }
    }

    });

I am getting this error for the following line.

Variable is not assignable (missing __block type specifier) at line

 stringArray =  [self.ParsingArray copy];

There are at least two StackOverflow questions that address this error. It doesn't have to do with Swift; it has to do with using a "block" (Objective-C name for a "closure" in Swift). [Assign a variable inside a Block to a variable outside a Block](https://stackoverflow.com/q/7962721/1107226) and [“variable is not assignable (missing __block type specifier)” error when using a variable from method declaration in method block](https://stackoverflow.com/q/36573957/1107226) — leanne, Oct 28 '17 at 15:31

score 0 · Accepted Answer · answered Oct 28 '17 at 15:28

You are trying to modify the value of the stringArray function parameter within a block, so you should tell that to the compiler. You could try making a copy right before the dispatch_sync call as such:

    __block NSArray *stringArrayCopy = [stringArray copy];

and use the copy within the block.

This will silence the compiler errors, but please note that if your intention is to change your Swift videosAutoCompletion array by setting the stringArray parameter within the ObjC method, you need to change your approach. Setting stringArray = [self.ParsingArray copy]; only has an effect local to the autocompleteSegesstions::: function.

Passing an NSArray from Swift into Objective-C function

1 Answers1