Question

我有一个用Swift编写的iOS应用，我在UIWebView中加载了一个网页。我添加了一个Javascript接口，该接口公开了Swift中的某些功能，这些功能在网页上通过Javascript桥调用。我希望公开一个新功能，该功能允许我打开UIImagePickerController，允许用户从图库中选择图像。当我从选择器收到回调中的图像后，我希望将图像传输到网页。因此，我尝试获取图像的文件路径（使用从选择器委托方法获得的图像信息中使用键UIImagePickerControllerImageURL），并将其传递给Javascript上下文，该上下文在html中更新了一个img标记，指向该图像src到文件路径。文件路径读为

file:///private/var/mobile/Containers/Data/Application/D28F50B5-4BC2-4D6C-9107-2831384542FE/tmp/290042B5-9302-417E-840C-1B410F3B824B.jpeg

但是图像资产无法在Web视图中呈现。我实现的另一种解决方案是将UIImage数据转换为易于传递的base64字符串，但是这种方法在这里处理大图像是一个问题。是否可以获取可以由webview加载的所选图像资产的文件路径？还有其他替代方法吗？

import UIKit

导入照片

ViewController类：UIViewController，UIImagePickerControllerDelegate，UINavigationControllerDelegate {

private var webView: UIWebView!

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    webView = UIWebView()
    self.view.addSubview(webView)
}

public func openGalleryAndPickImage(){
    presentImagePicker(presentingViewController: self, pickerSourceType: .photoLibrary)
}

public func takeImageWithCamera(){
    presentImagePicker(presentingViewController: self, pickerSourceType: .camera)
}

private func presentImagePicker(presentingViewController: UIViewController, pickerSourceType: UIImagePickerController.SourceType){
    let picker = UIImagePickerController()
    picker.delegate = self
    picker.sourceType = pickerSourceType
    picker.allowsEditing = false
    presentingViewController.present(picker, animated: true, completion: nil)
}

public func imagePickerController(_ picker: UIImagePickerController,
                                  didFinishPickingMediaWithInfo info: [String : Any]) {
    picker.dismiss(animated: true, completion: nil)
    convertImageToBase64AndCallJS(image: info[UIImagePickerControllerOriginalImage] as! UIImage)
}

public func imagePickerControllerDidCancel(_ picker: UIImagePickerController){
    picker.dismiss(animated: true, completion: nil)

}

private func convertImageToBase64AndCallJS(image: UIImage) {
    let base64String = base64EncodedStringWith(image: image)
    callJSFunctionFromSwift(img: base64String)
}

private func base64EncodedStringWith(image: UIImage)->String{
    let imageData = UIImagePNGRepresentation(image)
    return imageData?.base64EncodedString() ?? ""
}

private func callJSFunctionFromSwift(img: String) {
    webView?.stringByEvaluatingJavaScript(from: "processImage('\(img)')")
}

}

通过Javascript桥传递图像

0 个答案: