从目标C传递一个块到C ++方法 [英] Pass a block to a C++ method from objective C

问题描述

我有一个C + +辅助类，我使用与目标C。我想从视图控制器（回调）传递c ++类的一个块，以便当它被执行时，我在主线程，并可以更新UI。我当前有一个类似的系统使用函数指针和 performSelector 时调用该函数。我想要一个如何设置c ++变量以及如何传递一个目标C块并从c ++类调用它的示例。

I have a C++ helper class that I use with objective-C. I would like to pass the c++ class a block from a view controller (a callback) so that when it is executed I am on the main thread and can update the UI. I currently have a similar system working with function pointers and performSelector when the function is called. I would like an example of how to set up the c++ variable and how to pass an objective-C block to it and call it from the c++ class.

如果这是不可能，你能想到另一个/更好的解决方案吗？

If this is not possible, can you think of another/better solution?

推荐答案

所以只是你不完全熟悉块语法？如果是这样，这是一个快速的例子，如果你已经熟悉函数指针（语法或多或少相同，但使用 ^ 为声明一个[创建一个闭包是，当然是不同的]。

So is it just that you're not entirely familiar with the block syntax? If so, here's a quick example that should hopefully make sense if you're already familiar with function pointers (the syntax is more or less the same, but with the use of an ^ for declaring one [creating a closure is, of course, different]).

你可能想为块类型设置一个typedef只是为了保存自己重复同样的事情一遍又一遍，但我包括使用typedef的例子，只是把块类型本身放在参数中。

You probably want to set up a typedef for the block types just to save yourself repeating the same thing over and over, but I included examples for both using a typedef and just putting the block type itself in the parameters.

#import <Cocoa/Cocoa.h>

// do a typedef for the block
typedef void (^ABlock)(int x, int y);

class Receiver
{
public:
    // block in parameters using typedef
    void doSomething(ABlock block) {
        block(5, 10);
    }

    // block in parameters not using typedef
    void doSomethingToo(void (^block)(int x, int y)) {
        block(5, 10);
    }
};


int main (int argc, char const *argv[])
{
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    Receiver rcv;
    // pass a block
    rcv.doSomething(^(int x, int y) { NSLog(@"%d %d", x, y); });
    rcv.doSomethingToo(^(int x, int y) { NSLog(@"%d %d", x, y); });

    [pool drain];
    return 0;
}

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