如何使用PHPicker在iOS系统无授权下获取资源

let photoLibrary = PHPhotoLibrary.shared()
var config = PHPickerConfiguration(photoLibrary: photoLibrary)
                        
let selectedCount = self.albumViewModel.selectArray.count
let limited = min(4-selectedCount, 4)
config.selectionLimit = (type == .pic ? limited : 1)
config.filter = (type == .pic ? .images : .videos)
let pickerViewController = PHPickerViewController(configuration: config)
pickerViewController.delegate = self
self.viewController?.present(pickerViewController, ani

下面这段代码是网络上广泛被转载的一段错误代码：

import UIKit
import PhotosUI
class PhotoKitPickerViewController: UIViewController, PHPickerViewControllerDelegate {
    @IBAction func presentPicker(_ sender: Any) {
        let photoLibrary = PHPhotoLibrary.shared()
  let configuration = PHPickerConfiguration(photoLibrary: photoLibrary)
  let picker = PHPickerViewController(configuration: configuration)
  picker.delegate = self
  present(picker, animated: true)
 }
  
 func picker(_ picker: PHPickerViewController, didFinishPicking results: [PHPickerResult]) {
  picker.dismiss(animated: true)
  let identifiers = results.compactMap(\.assetIdentifier)
  let fetchResult = PHAsset.fetchAssets(withLocalIdentifiers: identifiers, options: nil)
    
  // TODO: Do something with the fetch result if you have Photos Library access
 }
}

func picker(_ picker: PHPickerViewController, didFinishPicking results: [PHPickerResult]) {
    picker.dismiss(animated: true)
    for result in results {
        let itemProvider: NSItemProvider = result.itemProvider;
        if(itemProvider.hasItemConformingToTypeIdentifier(UTType.image.identifier)) {
            // 图片处理
        } else  if(itemProvider.hasItemConformingToTypeIdentifier(UTType.movie.identifier)) {
            // 视频处理
        } else {
            // 其他，暂时忽略
        }
    }
}

func picker(_ picker: PHPickerViewController, didFinishPicking results: [PHPickerResult]) {
    picker.dismiss(animated: true)
    for result in results {
        let itemProvider: NSItemProvider = result.itemProvider;
        if(itemProvider.hasItemConformingToTypeIdentifier(UTType.image.identifier)) {
            // 图片处理
            itemProvider.loadDataRepresentation(forTypeIdentifier: UTType.image.identifier) { data, error in
                    //处理业务model转换
                    if let model = self.createPhotoResourcesModel(data: data, assetIdentifier: assetIdentifier){
                        self.albumViewModel.selectArrayAddObject(model)
                        
                        DispatchQueue.main.async {
                            //更新UI
                        }
                    }
              }
            
        } else  if(itemProvider.hasItemConformingToTypeIdentifier(UTType.movie.identifier)) {
            // 视频处理
        } else {
            // 其他，暂时忽略
        }
    }
}

let imgSrc = CGImageSourceCreateWithData(data, options as CFDictionary)
let metadata = CGImageSourceCopyPropertiesAtIndex(imgSrc, 0, options as CFDictionary)
colorModel = metadata[kCGImagePropertyColorModel] as? String
pixelWidth = metadata[kCGImagePropertyPixelWidth] as? Double;
pixelHeight = metadata[kCGImagePropertyPixelHeight] as? Double;

这里我们使用了Github上开源的 ExifData（2） 代码，完整实现了所有字段的获取封装，使用起来非常方便。

func createPhotoResourcesModel(data:Data?,
                            assetIdentifier:String?) -> SNSResourcesModel? {
        guard let imageData = data, let uiimage = UIImage(data: imageData) else {
            return nil
        }
        let model = SNSResourcesModel()
        model.assetLocalIdentifier = assetIdentifier
        model.assetType = .photo
        model.assetSource = .album
        model.originImage = uiimage
        model.bigPreviewImage = uiimage
        
        let exifData = ExifData(data: imageData)
        model.pixelWidth = Int(exifData.pixelWidth ?? 0)
        model.pixelHeight = Int(exifData.pixelHeight ?? 0)
        if imageData.imageType == .GIF{
            model.isGif = true
            model.gifData = imageData
        }
        return model
}

if(itemProvider.hasItemConformingToTypeIdentifier(UTType.image.identifier)) {
    // 图片处理
    // 判断webp
    if itemProvider.hasItemConformingToTypeIdentifier(UTType.webP.identifier){
        //处理webp
    }
    //判断GIF
    if itemProvider.hasItemConformingToTypeIdentifier(UTType.gif.identifier){
        //处理GIF
    }        
}

获得视频时，推荐使用loadFileRepresentation，返回URL，通过URL可以获得 AVAsset。

func picker(_ picker: PHPickerViewController, didFinishPicking results: [PHPickerResult]) {
    picker.dismiss(animated: true)
    for result in results {
        let itemProvider: NSItemProvider = result.itemProvider;
        if(itemProvider.hasItemConformingToTypeIdentifier(UTType.image.identifier)) {
            // 图片处理
        } else  if(itemProvider.hasItemConformingToTypeIdentifier(UTType.movie.identifier)) {
            // 视频处理
            itemProvider.loadFileRepresentation(forTypeIdentifier: UTType.movie.identifier) { url, error in
                    //业务model转换
                    if let model = self.createVideoResourcesModel(url: url, assetIdentifier: assetIdentifier){
                        self.albumViewModel.selectArrayAddObject(model)
                        
                        DispatchQueue.main.async {
                            //展示UI
                        }
                    }
            }
        } else {
            // 其他，暂时忽略
        }
    }
}

当获取的资源文件较大时，我们需要获得加载数据的进度，此时可以使用 NSItemProvider的加载数据函数提供的返回值NSProgress对象。

var progress:Progress?
progress = itemProvider.loadDataRepresentation(forTypeIdentifier: UTType.image.identifier) { data, error in
    //...
}
//添加观察者
progress?.addObserver(self, forKeyPath: "fractionCompleted", options: [.new], context: nil)

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    if keyPath == "fractionCompleted" {
        print("fractionCompleted=\(self.progress?.fractionCompleted)")
    }
}

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