发件人在prepareForSegue：sender调用中是什么？

Question

Suppose I perform a segue change when a button is tapped as given in the code below.

- (IBAction)btnTapped:(id)sender {   
    [self performSegueWithIdentifier:@"login" sender:self];
}

I'm wondering the purpose of the "sender" part. Does it make difference if I make the call with the parameter sender:sender , sender:@{@"foo",@"bar"} or sender:nil ??

Edit1:

Can I get this sender at the destination ViewController for instance at ViewDidLoad() function?

Answer 1

The Apple's documentation :

sender:

The object that you want to use to initiate the segue.

This object is made available for informational purposes during the actual segue.

If you want to use sender object in the target UIViewController , use prepareForSegue:sender: method:

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    // Make sure your segue name in storyboard is the same as this line
    if ([[segue identifier] isEqualToString:@"YOUR_SEGUE_NAME_HERE"])
    {
        ....
    }
}

Answer 2

无论使用哪种方法，都设置了sender属性，因此您只需将（id）sender显式转换为（MyAnteriorView *）sender，就可以轻松地从前视图中检索信息。