复制或保留块时为EXC_BAD_ACCESS [英] EXC_BAD_ACCESS when copying or retaining Block

问题描述

据我所知，块的作用类似于对象，因为您可以向其发送复制或释放消息，例如:

As far as I understand a Block acts like an object, in that you can send copy or release messages to it, e.g:

[myBlock copy];

但是无论何时执行此操作或释放一个块，我都会得到EXC_BAD_ACCESS.

However whenever I do this, or release a block, I get EXC_BAD_ACCESS.

如果我使用块函数，那么一切都会按预期进行，例如:

If I use the block functions, everything works as expected, e.g.:

Block_copy(myBlock);

我认为释放和复制块的方式是相同的吗?

I thought both ways of releasing and copying blocks were identical?

问题不大，但是如果我有一个属性(副本)是一个块，那我就必须自己编写setter方法.

It's not that much of a problem, but it is a little annoying that if I have a property (copy) which is a Block, I have to write the setter method myself.

例如:具有属性:

//Header
@property (nonatomic, copy) void (^cancelledBlock)(void);

//Implementation
@sythesize cancelledBlock;

设置cancelledBlock

导致EXC_BAD_ACCESS

但如果我这样做:

but if I do:

//Header
@property (nonatomic, copy) void (^cancelledBlock)(void);

//Implementation
@sythesize cancelledBlock; //saves me doing the getter as well

- (void)setCancelledBlock:(void (^)(void))aCancelledBlock {
    if (cancelledBlock == aCancelledBlock) {
        return;
    }
    void (^oldValue)(void) = cancelledBlock;
    cancelledBlock = Block_copy(aCancelledBlock);
    Block_release(oldValue);

}

没有EXC_BAD_ACCESS，一切运行正常.

there is no EXC_BAD_ACCESS and everything runs as it should.

推荐答案

在漫长而无聊的下午和傍晚之后，我终于遇到了这个

After a long and boring afternoon and evening I finally came across this answer here, although it may seem unrelated, the chain of websites I visited to find it, creates that relation.

基本上，我必须从链接器标志中删除-weak_library /usr/lib/libSystem.B.dylib并将其替换为-weak-lSystem.

Basically I had to remove -weak_library /usr/lib/libSystem.B.dylib from the linker flags and replace it with -weak-lSystem.

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