swift - imagePicker 一旦您从库中选择一张照片，就不允许您选择另一张照片

Question

正如标题所示，我正在尝试在您选择照片后提供更改照片的可能性。目前，如果用户不取消选择前一张照片，则无法选择另一张照片，因此我对选择多张照片不感兴趣，而只是每次触摸时都能移动光标。

fileprivate func showImagePicker(sourceType: UIImagePickerControllerSourceType) {
        let imagePickerVC = UIImagePickerController()

        imagePickerVC.sourceType = sourceType
        imagePickerVC.delegate = self
        imagePickerVC.allowsEditing = true

        present(imagePickerVC, animated: true, completion: nil)
}

Answer 1

UIImagePickerController 不允许选择多个图像。查看此问题的最佳答案:How to select Multiple images from UIImagePickerController - 有一个很长的链接列表，提供有用的外部 API 和库。我会选择OpalImagePicker对于这个例子。 OpalImagePicker 有一个选项用于设置用户可以选择的图像的最大限制，这意味着可以选择多个图像。例如，您可以通过编写行 imagePicker.maximumSelectionsAllowed = 10 将其设置为 10 个图像。这是一个很棒的 AP​​I，允许您根据自己的控件自定义图像选择器。它具有 Swift 4 和 Swift 5 兼容性。它甚至提供委托(delegate)方法来从 Facebook、Instagram 或 Twitter 等外部来源选取图像。

要安装，请转到CocoaPods ，然后输入:

pod 'OpalImagePicker'

示例代码:

import OpalImagePicker

class DelegateExampleViewController: UIViewController {
    @IBAction func photoLibraryTapped(_ sender: UIButton) {
        let imagePicker = OpalImagePickerController()
        imagePicker.imagePickerDelegate = self
        imagePicker.selectionTintColor = UIColor.white.withAlphaComponent(0.7)
        imagePicker.selectionImageTintColor = UIColor.black
        imagePicker.selectionImage = UIImage(named: "x_image")  // Change image to X rather than checkmark
        imagePicker.statusBarPreference = UIStatusBarStyle.lightContent
        imagePicker.maximumSelectionsAllowed = 10  // This is the line that relates to your question
        let configuration = OpalImagePickerConfiguration()
        configuration.maximumSelectionsAllowedMessage = NSLocalizedString("You cannot select that many 
             images!", comment: "")
        imagePicker.configuration = configuration
        present(imagePicker, animated: true, completion: nil)
    }
}

extension DelegateExampleViewController: OpalImagePickerControllerDelegate {
    func imagePickerDidCancel(_ picker: OpalImagePickerController) {
        // Cancel action
    }

    func imagePicker(_ picker: OpalImagePickerController, didFinishPickingImages images: [UIImage]) {
        // Save Images, update UI   
        // Dismiss Controller
        presentedViewController?.dismiss(animated: true, completion: nil)
    }

    func imagePickerNumberOfExternalItems(_ picker: OpalImagePickerController) -> Int {
        return 1
    }

    func imagePickerTitleForExternalItems(_ picker: OpalImagePickerController) -> String {
        return NSLocalizedString("External", comment: "External (title for UISegmentedControl)")
    }

    func imagePicker(_ picker: OpalImagePickerController, imageURLforExternalItemAtIndex index: Int) -> URL? {
        return URL(string: "https://placeimg.com/500/500/nature")
    }
}