objective-c-blocks

I know that a block is a reusable chunk of executable code in Objective-C. Is there a reason I shouldn't put that same chunk of code in a function and just called the function when I need that code to run? It depends on what you're trying to accomplish. One of the cool things about blocks is that they capture local scope. You can achieve the same end result with a function, but you end up having to do something like pass around a context object full of relevant values. With a block, you can do this: int num1 = 42; void (^myBlock)(void) = ^{ NSLog(@"num1 is %d", num1); }; num1 = 0; // Changed

http://clang.llvm.org/docs/BlockLanguageSpec.txt Looks really cool. However, I don't understand it. I don't see examples it. I don't see examples of ideas hard to express in C++ as is, but trivial to express in blocks. Can anyone enlighten me on this? Blocks are, essentially, a way to pass code and scope around as data. They're known in some other languages as closures and anonymous functions. Here's an article with more details and code examples. NanoTech already linked to an explanation of blocks. As for how this relates to C++ let me state my personal opinion: This extension is not useful

Under normal conditions, when a block is declared to return a value, but no return statement actually appears in the block, Clang fails to compile it with an error (of a missing return value). However, this breaks when that block contains @try{} @catch(...){} or @try{} @finally{} . Does anyone know why? The way I found this was when using @weakify() and @strongify() in RACExtScope in ReactiveCocoa, in one block I forgot to return a signal. But the compiler didn't warn me and crashed on runtime, which lead me to dig into it, preprocess the code and find that this causes it. Any explanation