相关疑难解决方法(0)

我有一个关于iOS中块的自我强弱参考的问题.我知道在块内引用self的正确方法是在块外创建一个弱引用,然后在块内强引用该弱引用,如下所示:

__weak typeof(self) weakSelf = self;
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^ {
    typeof(self) strongSelf = weakSelf;
    NSLog(@"%@", strongSelf.someProperty);
});

但是,如果你有嵌套块会发生什么？一组参考文献足够吗？或者您是否需要为每个区块设置新组？例如,以下哪项是正确的？

这个:

__weak typeof(self) weakSelf = self;
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^ {
    typeof(self) strongSelf = weakSelf;
    NSLog(@"%@", strongSelf.someProperty);
    dispatch_async(dispatch_get_main_queue(), ^ {
        strongSelf.view.frame = CGRectZero;
    });
});

或这个:

__weak typeof(self) weakSelf = self;
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^ {
        typeof(self) strongSelf = weakSelf;
        NSLog(@"%@", strongSelf.someProperty);
        __weak typeof(strongSelf) weakSelf1 = strongSelf;
        dispatch_async(dispatch_get_main_queue(), ^ {
            typeof(strongSelf) strongSelf1 = weakSelf1;
            strongSelf1.view.frame = CGRectZero;
        });
    });

非常感谢任何信息或解释!

我想了解这段代码:

__weak LoginViewController *weakSelf = self;

NSTimer *networkTimer = [NSTimer pym_scheduledTimerWithTimeInterval:15.0 block:^{
    LoginViewController *strongSelf = weakSelf;
    [strongSelf timeout];
} repeats:NO];

[PYMAuthManager loginWithUsername:username password:password completionHandler:^(BOOL successful) {
    if (successful) {
        [networkTimer invalidate].......

这是一个网络计时器,如果没有活动,将在15秒后超时.为什么在块中创建指针*strongSelf = weakSelf？使用[weakSelf timeout]不行吗？我明白无论何时在块中访问self我们都必须使用弱引用,为什么在这里创建另一个指针？任何帮助都会很棒,谢谢.