ios - UIImagePickerController 可以直接在 Story Board 上使用吗？

Question

我的印象是 ViewController 的用法是相似的:在 Storyboard上，我们将一个 UIViewController 拖到场景上，然后更改它的类类型，例如到 UIImagePickerController。 (我想做一个专门的取图场景)

但后来我发现如果我直接子类化，UIImagePickerController 将无法工作:

class TestUIImagePickerController: UIImagePickerController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()
        self.sourceType = .photoLibrary
        self.delegate = self
        // self.present(self, animated: true) // either comment it out or not, both way won't work. 
    }

但它只有在我将一个 UIViewController 放在 Storyboard上，然后以编程方式构造一个 UIImagePickerController 时才有效:

class SecondTestUIImagePickerController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()

        let picker = UIImagePickerController()
        picker.sourceType = .photoLibrary
        picker.delegate = self
        self.present(picker, animated: true)
    } 

我可以知道我在第一个用法示例中是否遗漏了什么吗？是否必须以编程方式创建 UIImagePickerController 然后通过代理 View Controller (UIVIewController) 呈现它？

Answer 1

self.present(self, animated: true) 

你不能self呈现self，使用另一个ViewController来呈现UIImagePickerController

UIImagePickerController 可以在 Story board 上使用，例如在您的代码中

class SecondTestUIImagePickerController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()
        let sb = UIStoryboard(name: "ImagePickerStoryboard", bundle: nil)
        let picker = sb.instantiateViewControllerWithIdentifier("ImagePicker") as! TestUIImagePickerController
        self.present(picker, animated: true)
}

请记住 UIImagePickerController 是 UINavigationController 的子类