250 Views 2 Replies
      Latest reply on Nov 20, 2016 4:52 PM by stcocoa
      stcocoa Level 1 Level 1 (0 points)
      stcocoa Nov 17, 2016 7:01 PM

        Hi ,

         

        I have a method retruning boolean value, buy I use block in this method to do network.

         

        And I just want to return true or false in this block.

         

        But I couldnt because there is a error as below.

         

        Return type 'int' must match previous return type 'void' when block literal has unspecified explicit return type

         

        oh.. any way to solve those problem ?

         

        Thanks

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        • Re: Any way to return value in a block
          eskimo Apple Staff Apple Staff (11,505 points)
          eskimo Nov 18, 2016 2:29 AM (in response to stcocoa)

          Presumably you have code like this:

          BOOL (^b)(int someParam);

b = ^(int someParam){
    return someParam > 0;
};

          and are getting this error on line 3.  The issue here is that someParam > 0 is of type int, so the inferred type of the block is int (^)(int), which is not compatible with the type of b, that is, BOOL (^)(int).

          There are two ways to fix this.  First, you could force the type of the block:

          b = ^BOOL(int someParam){
    return someParam > 0;
};

          Alternatively, you could force the type that you return so that the type of the block in inferred correctly:

          b = ^(int someParam){
    return (BOOL) (someParam > 0);
};

          IMPORTANT In this second case I added some parens so that the cast applies to the whole result, not to just someParam.

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