iOS：如何讓ViewController A模態地呈現B，然后直接將B取消/轉換為模態呈現的C？

Question

現在，我有一個ViewController（“ A”）以模態形式呈現用戶的iPod庫（“ B”）：

// This works great
- (void)selectSong { // UIBarButtonSystemItemAdd target action
    MPMediaPickerController *picker = [[MPMediaPickerController alloc] init];
    picker.delegate = self;
    [self presentViewController:picker animated:YES completion:NULL];
}

我通過委托從“ A”內部取消了模態呈現的VC“ B”：

- (void)mediaPicker:(MPMediaPickerController *)mediaPicker didPickMediaItems:(MPMediaItemCollection *)mediaItemCollection {
    // Do stuff with selected item...

    // Set up modal transition style and then dismiss
    [mediaPicker setModalTransitionStyle:UIModalTransitionStyleFlipHorizontal];
    [mediaPicker dismissViewControllerAnimated:YES completion:^{
        // Launch capture screen
        // DOING IT THIS WAY CLEARLY SHOWS VIEW "A" BEFORE WE SEE VIEW "C"
        // I'M LOOKING FOR A WAY I CAN DISMISS THE MODAL IPOD MUSIC PICKER
        // VIA "FLIP" DIRECTLY TO VIEW CONTROLLER "C" (WHICH DOES SOMETHING
        // WITH THE SELECTED SONG).
        [self performSegueWithIdentifier:@"captureViewController" sender:self];
    }];
}

通過這種實現，從技術上講，一切都可以工作。 我不喜歡ViewController A同時顯示B和C的方式，用戶可以在關閉B之后再顯示C之前看到ViewControllerA。我希望A顯示B，然后B直接將其釋放/轉換為C.我怎樣才能做到這一點？

*更新：還請注意，如果我將手動segue調用放在補全代碼塊之外，那么會出現有關一次顯示兩件事的錯誤。 如果我將動畫設置為“否”，則會收到另一個錯誤。

Answer 1

在故事板中給captureViewController一個標識符。

- (void)mediaPicker:(MPMediaPickerController *)mediaPicker didPickMediaItems:(MPMediaItemCollection *)mediaItemCollection {
    // Do stuff with selected item...

    // Set up modal transition style and then dismiss

    UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:@"STORYBOARDNAME" bundle:nil];
    UIViewController *vc = [mainStoryboard instantiateViewControllerWithIdentifier:@"captureViewController"];
    [self presentModalViewController:vc animated:NO];

    [mediaPicker setModalTransitionStyle:UIModalTransitionStyleFlipHorizontal];
    [mediaPicker dismissViewControllerAnimated:YES completion:nil];
}

Answer 2

試試這個，

- (void)selectSong { // UIBarButtonSystemItemAdd target action
    MPMediaPickerController *picker = [[MPMediaPickerController alloc] init];
    picker.delegate = self;
 [self performSegueWithIdentifier:@"captureViewController" sender:self];
    }];
    [self presentViewController:picker animated:YES completion:NULL];
}