iOS メソッドの引数でBlocksを使う方法

typedef void (^TestMethodBlock)(BOOL arg1, BOOL arg2);

- (void)testMethodWithCompletion:(TestMethodBlock)_completion {

    TestMethodBlock completion = [_completion copy];

    // 別スレッド
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0),^{

        /// 時間のかかる処理 ///

        // メインスレッド
        dispatch_sync(dispatch_get_main_queue(), ^{
            completion(YES, YES);
        });
    });
}

呼び出

    [self testMethodWithCompletion:^(BOOL arg1, BOOL arg2) {

    }];