How Do I Declare A Block in Objective-C?

As a local variable:


      returnType (^blockName)(parameterTypes) = ^returnType(parameters) {...};

As a property:


      @property (nonatomic, copy, nullability) returnType (^blockName)(parameterTypes);

As a method parameter:


      - (void)someMethodThatTakesABlock:(returnType (^nullability)(parameterTypes))blockName;

As an argument to a method call:


      [someObject someMethodThatTakesABlock:^returnType (parameters) {...}];

As a parameter to a C function:


      void SomeFunctionThatTakesABlock(returnType (^blockName)(parameterTypes));

As a typedef:


      typedef returnType (^TypeName)(parameterTypes);

      TypeName blockName = ^returnType(parameters) {...};

This site is not intended to be an exhaustive list of all possible uses of blocks.
If you find yourself needing syntax not listed here, it is likely that a typedef would make your code more readable.

Unable to access this site due to the profanity in the URL? http://goshdarnblocksyntax.com is a more work-friendly mirror.