ios - iOS performSelectorInBackground内部的performSelectorInBackground

Question

似乎该函数调用[self updateUI];被嘘封锁。

boo是在另一个后台线程中运行还是与foo相同，如下面的代码？

[self updateUI]如何？不被嘘阻止吗？

- (void)MainFunction
{
    [self performSelectorInBackground@selector(foo) withObject:nil];
}

- (void)foo
{
    [self performSelectorInBackground@selector(boo) withObject:nil];

    //updaate UI in MainThread
    [self updateUI];
}

- (void)boo
{
    //function here take long time to run;
}

Answer 1

在您的代码中，似乎在后台中调用foo，因此无法在后台线程中更新 UI，因为您需要在主线程中进行此操作。无论如何，performSelectorInBackground有点旧...以这种方式使用dispatcher:

- (void)MainFunction
{
    [self foo];
}

- (void)foo
{
    dispatch_async(dispatch_get_global_queue(DISPATCH_PRIORITY_DEFAUL, 0ull), ^{
        [self boo];

        dispatch_async(dispatch_get_main_queue(), ^{
            //updaate UI in MainThread
            [self updateUI];
        };
    };
}

- (void)boo
{
    //function here take long time to run;
}

在这种情况下， updateUI 等待 boo ，但是如果您想先 updateUI ，并且 boo 何时完成无关紧要:

- (void)foo
{
    dispatch_async(dispatch_get_global_queue(DISPATCH_PRIORITY_DEFAUL, 0ull), ^{
        [self boo];
    };

    [self updateUI];
}