This chapter is from the book
This chapter is from the book
This chapter is from the book
This chapter is from the book
Block Variables
Blocks are not limited to living in-line in method or function calls. You can have variables, whether local, global, or instance, that point to blocks. The syntax is like standard C function pointer syntax but using a caret instead of a star:
void (^blockPtrVar) (NSString *arg) = ^(NSString *arg) { NSLog (@"%@", arg); };
The name of the variable is blockPtrVar. The block returns nothing (void) and takes a single NSString argument.
Invoke it like a function pointer:
blockPtrVar (@"hello");
which prints "hello."
Things become more readable when you use a typedef:
typedef void (^BlockType) (NSString *arg);
BlockType blockPtrVar = ^(NSString *arg) { NSLog (@"%@", arg); };
blockPtrVar (@"there");
which prints out "there" as you would expect.