UIView使用代理呈现UIViewController

Question

I have a UIViewController that pops up a custom UIView that needs to be able to present another UIViewController ( BarcodeScanViewController ).

When the user is done with the BarcodeScanViewController , data is passed back to the UIView to update a label.

How can I present the BarcodeScanViewController from the UIView with the a navigation bar so I close it if necessary?

The below code kinda works. It present the BarcodeScanViewController , but it doesn't actually do anything. Its just a black view.

Inside Custom UIView

- (void) startScan {

    BarcodeScanViewController * bsvc = [[BarcodeScanViewController alloc] init];
    bsvc.delegate = self;

    UIViewController *currentTopVC = [self currentTopViewController];
    [currentTopVC presentViewController:bsvc animated:YES completion:nil];

}

I also receive an warning

Assigning to

'id < BarcodeScanViewControllerDelegate > ' from incompatible type 'CustomView * const__strong'

when I try to assign the delegate.

I have never called UIViewController from a UIView before. I know that only a VC can call another VC. So I tried to create VC to use a presenter.

What am I doing wrong?

Answer 1

Okay, there were a bunch of smaller things. I forked your repo and fixed it so that you can see how it works. See here .

In short: You did present the scanner VC, but as I said you can't simply put it "over" the presenting view controller (your ViewController class). As soon as any presentation transitions (ie animations) are done, the view of that ViewController is removed from the view hierarchy. So what you saw as a black screen was just the window background (which is black). The scanner's view was transparent. Furthermore, the scanner expected you to provide a view to render the camera into (and buttons) via an IBOutlet. Since you didn't instantiate the controller from a storyboard, you didn't set any, ie the view used for that was nil and thus the frame the scanner wanted to render the video in had a size of (0, 0). I fixed that for now, hopefully you can now see how presenting a viewcontroller is supposed to work. To achieve an actual popup (with "underlying views of previous view controllers") is a bit harder on iOS, but possible in several ways. I can elaborate further later if you want.