保存实例变量中的块 [英] Saving a block in instance variable

问题描述

我们如何声明一个全局（私有实例变量）来接受一个块。我们需要合成它，

How do we declare a global(private instance variable) to accept a block in it. Do we need to synthesis it & what are the memory management implications with it.

我有一个从第三方方法接收的块，我想保存在实例变量&

I have a block received from a third party method which I want to save in the instance variable & use it at a later stage.

推荐答案

这里是一个（无ARC）的例子，在完成回调后存储一个块一些工作在后台：

Here's an (ARC-less) example of storing a block for a completion callback after doing some work in the background:

Worker.h：

@interface Worker : NSObject
{
    void (^completion)(void);
}
@property(nonatomic,copy) void (^completion)(void);
- (void)workInBackground;
@end

Worker.m：

@implementation Worker
@synthesize completion;

- (void)dealloc
{
    Block_release(completion);

    [super dealloc];
}

- (void)setCompletion:(void (^)(void))block
{
    if ( completion != NULL )
        Block_release(completion);

    completion = Block_copy(block);
}

- (void)workInBackground
{
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void)
    {
        // Do work..

        dispatch_async(dispatch_get_main_queue(), completion);
    });
}

@end

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