objective-c - 在 block 中使用弱 obj 时崩溃

Question

我的代码是这样的:

Member *member = [Member new];
__weak __typeof(self) weakSelf = self
member.gotoPageBlock = ^(NSString *url) {
    __strong __typeof(weakSelf) self = weakSelf
    [self goToPageWithURL:[NSURL URLWithString:url]];
};

它很少会崩溃，这个崩溃的顶部堆栈是这样的:

Exception Type:  SIGSEGV
Exception Codes: SEGV_ACCERR at 0x365722298
Triggered by Thread:  0
Thread 0 Crashed:
0   libobjc.A.dylib                 0x0000000182794bb4 _objc_loadWeakRetained :156 (in libobjc.A.dylib)

执行 block 时发生崩溃。
有谁知道发生了什么？

Answer 1

不需要再次创建 strong self ，因此删除此行 __strong __typeof(weakSelf) self = weakSelf 然后应该可以正常工作

使用这个

Member *member = [Member new];
__weak __typeof(self) weakSelf = self
member.gotoPageBlock = ^(NSString *url) {
    //the difference is here
    [weakSelf goToPageWithURL:[NSURL URLWithString:url]];
};

检查 https://sectionfive.net/blog/2014/11/24/arc-exploration-and-pitfalls/在在执行时失去所有权部分了解更多信息