Wrapping C++ functions into blocks - c++

Question

In my app i have a C++ class and an Objective-c class working together the following way:
PingPong.h
#ifndef __RSSCPPCallbackTest__PingPong__h
#define __RSSCPPCallbackTest__PingPong__h
#include <iostream>
class PingPong
{
public:
static void requestPingPongWithText(std::string text);
static void eventRequestPingPongWithTextSuccess(std::string successString);
static void eventRequestPingPongWithTextFailure(std::string failureString);
};
#endif
PingPong.cpp
#ifndef __RSSCPPCallbackTest__PingPong__m
#define __RSSCPPCallbackTest__PingPong__m
#include "PingPong.h"
void PingPong::requestPingPongWithText(std::string text)
{
if (text.compare("ping") == 0)
{
PingPong::eventRequestPingPongWithTextSuccess("success ping");
}
else
{
PingPong::eventRequestPingPongWithTextFailure("failure pong");
}
}
#endif
Objective-C class: MainViewController.mm
#implementation MainViewController
/* init, viewDidLoad, etc... */
// Call ping with a button
- (IBAction)sayPing:(id)sender {
NSString *text = #"ping";
PingPong::requestPingPongWithText([text UTF8String]);
}
// Call pong with another button
- (IBAction)sayPong:(id)sender {
NSString *text = #"pong";
PingPong::requestPingPongWithText([text UTF8String]);
}
#end
void PingPong::eventRequestPingPongWithTextSuccess(std::string successString)
{
NSLog(#"successString: %#", [NSString stringWithCString:successString.c_str()
encoding:[NSString defaultCStringEncoding]]);
}
void PingPong::eventRequestPingPongWithTextFailure(std::string failureString)
{
NSLog(#"failureString: %#", [NSString stringWithCString:failureString.c_str()
encoding:[NSString defaultCStringEncoding]]);
}
This works fine. What i would like to do finally is to wrap this into a function with a completion block looking like:
[self requestPingPongWithText: text
completion:^(NSString *successString, NSString *failureString)) completion {
if (successString) {
NSLog(#"successString: %#", successString); }
else if (failureString) {
NSLog(#"failureString: %#", failureString); }
}];
How can i wrap up my existing code to have a function looking like above?

Answer 1

Lets make a new typdef in PingPong.h:
typedef void (^OnComplete)(std::string successString, std::string failureString);
Make a new method for the request by block:
static void requestPingPongWithBlock(std:string text, OnComplete block);
another way, to make it explicit:
static void requestPingPongWithBlock(std:string text, void (^block)(std::string successString, std::string failureString));
implementation in PingPong.cpp:
void PingPong::requestPingPongWithBlock(std::string text, OnComplete block)
{
if (text.compare("ping") == 0)
{
block("success ping", "");
}
else
{
block("", "failure pong");
}
}
in MainViewController.mm
-(void)requestPingPongWithText:(NSString*)text completion:(OnComplete) compblock{
PingPong::requestPingPongWithBlock([text UTF8String],compblock);
}
and you can call it like this way:
[self requestPingPongWithText: text
completion:^(std::string successString, std::string failureString) {
if (successString.length() != 0) {
NSLog([NSString stringWithUTF8String: successString.c_str()]); }
else if (failureString.length() != 0) {
NSLog([NSString stringWithUTF8String: failureString.c_str()]); }
}];
I hope it was helpful ;)