“Converting” a function pointer to a block in objective-C

Question

I\'m doing some Interop from Mono C# to Obj-C and ran into this problem. The C# code needs to pass a callback - which it does with a function pointer. I can get the function poi

Answer 1

What about

void (*myFunc)(int x); // ... your function pointer

void (^myBlock)(int) = ^(int x) {
    myFunc(x);
};

Then myBlock is a block that captures the value of the function pointer and calls the function when the block is executed.

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ADDED: My suggestion, based on your code, using a @property (and assuming that you compile with ARC):

FunctionToBlock.h:

typedef void (*DummyAction)(char * result);
typedef void (^DummyBlock)(char * result);

@interface FunctionToBlock : NSObject
{
    DummyAction function; // Not really needed.
}

- (id) initWithFunction: (DummyAction) func;
@property(copy, nonatomic) DummyBlock block;   // "copy" is important here!

@end

FunctionToBlock.m:

#import "FunctionToBlock.h"

@implementation FunctionToBlock : NSObject
@synthesize block = _block; // Can be ommitted if you use Xcode 4.4 or later.

- (id) initWithFunction: (DummyAction) func
{
    if (self = [super init]) {
        function = func; // Not really needed.
        self.block = ^(char * result) {
            func(result); // Use "func", not "self->function", to avoid retain cycle.
        };
    }
    return self;
}