FileManager/本地文件增删改查, Cache/图像缓存处理 的操作

1. FileManager 本地文件管理器，增删改查文件

  1.1 实现

// 本地文件管理器
class LocalFileManager{// 单例模式static let instance = LocalFileManager()let folderName = "MyApp_Images"init() {createFolderIfNeeded()}// 创建特定应用的文件夹func createFolderIfNeeded(){// 创建文件夹路径guard let path = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask).first?.appendingPathComponent(folderName).path else {return}// 判断文件夹是否存在，不存在，则创建文件夹路径if !FileManager.default.fileExists(atPath: path){do {try FileManager.default.createDirectory(atPath: path, withIntermediateDirectories: true)print("Success create folder.")} catch let error {print("Error creating folder. \(error)")}}}// 删除特定应用的文件夹func deleteFolder(){// 创建文件夹路径guard let path = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask).first?.appendingPathComponent(folderName).path else {return}do {try FileManager.default.removeItem(atPath: path)print("Success deleting filder.")} catch let error {print("Error deleting folder. \(error)")}}// 保存图片func saveImage(image: UIImage, name: String) -> String{// 压缩图片质量//image.jpegData(compressionQuality: 1.0)// 获取数据和文件路径guardlet data =  image.pngData(),let path = getPathForImage(name: name)else{return "Error getting data."}do{// 文件写入数据try data.write(to: path)return "Success saving."}catch let error{return "Error saving: \(error.localizedDescription)"}}// 获取图片func getImage(name: String) -> UIImage?{// 获取文件路径 absoluteString，并检查文件是否存在guard let path = getPathForImage(name: name)?.path,FileManager.default.fileExists(atPath: path) else{print("Error getting path.")return nil}return UIImage(contentsOfFile: path)}// 删除图片func deleteImage(name: String) -> String{// 获取文件路径，并检查文件是否存在guard let path = getPathForImage(name: name)?.path,FileManager.default.fileExists(atPath: path) else{return "Error getting path."}do {// 删除文件try FileManager.default.removeItem(atPath: path)return "Successfully deleted."} catch let error {return "Error deleting image: \(error)"}}// 获取文件路径func getPathForImage(name: String) -> URL?{// 文档目录//let directory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)// 缓存目录//let directory2 = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask).first// 临时目录//let directory3 = FileManager.default.temporaryDirectory// 拼接路径//let path = directory2?.appendingPathComponent("\(name).png")guardlet path = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask).first?.appendingPathComponent(folderName).appendingPathComponent("\(name).png") else {print("Error getting data.")return nil}print(path)return path}
}class FileManagerViewModel: ObservableObject{@Published var image: UIImage? = nillet imageName: String = "steve-jobs"let localManager  = LocalFileManager.instance@Published var infoMessage: String  = ""init() {getImageFromAssetsFoler()//getImageFromFileManager()}// 获取图片，在资源目录func getImageFromAssetsFoler(){image = UIImage(named: imageName)}// 获取图像，文件管理器func getImageFromFileManager(){image = localManager.getImage(name: imageName)}// 保存图像func saveImage(){guard let image = image else { return }infoMessage = localManager.saveImage(image: image, name: imageName)}// 删除图像func deleteImage(){infoMessage = localManager.deleteImage(name: imageName)localManager.deleteFolder()}
}/// 文件管理器
struct FileManagerBootcamp: View {@StateObject var viewModel = FileManagerViewModel()var body: some View {NavigationView {VStack {if let image = viewModel.image {Image(uiImage: image).resizable().scaledToFill().frame(width: 200, height: 200).clipped().cornerRadius(10)}HStack {Button {viewModel.saveImage()} label: {Text("Save to Fm").font(.headline).foregroundColor(.white).padding().padding(.horizontal).background(Color.accentColor).cornerRadius(10)}Button {viewModel.deleteImage()} label: {Text("Delete from Fm").font(.headline).foregroundColor(.white).padding().padding(.horizontal).background(Color.red).cornerRadius(10)}}Text(viewModel.infoMessage).font(.largeTitle).fontWeight(.semibold).foregroundColor(.purple)//.padding(.top, 20)Spacer()}.navigationTitle("File Manager")}}
}

  1.2 效果图

2. Cache 图像缓存处理操作

  2.1 实现

// 缓存管理器
class CacheManager {// 单例模式static let instance = CacheManager()private init() {}// 计算型属性 图像缓存var imageCache: NSCache<NSString, UIImage> = {let cache = NSCache<NSString, UIImage>()// 容纳最大对象的数量cache.countLimit = 100// 容纳最大值cache.totalCostLimit = 1024 * 1024 * 100 // 100mbreturn cache}()// 添加图像func add(image: UIImage, name: String) -> String{imageCache.setObject(image, forKey: name as NSString)return "Added to cache!"}// 移除图像func remove(name: String) -> String{imageCache.removeObject(forKey: name as NSString)return "Removed from cache"}// 获取图像func get(name: String) -> UIImage?{return imageCache.object(forKey: name as NSString)}
}// 缓存 ViewModel
class CacheViewModel: ObservableObject{@Published var startingImage: UIImage? = nil@Published var cachedImage: UIImage? = nil@Published var infoMessage: String = ""let imageName = "steve-jobs"let manager = CacheManager.instanceinit() {getImageFromAssetsFolder()}// 获取资源文件中图像func getImageFromAssetsFolder(){startingImage = UIImage(named: imageName)}// 保存图像func saveToCache(){guard let image = startingImage else { return }infoMessage = manager.add(image: image, name: imageName)}// 移除图像func removeFromCache(){infoMessage = manager.remove(name: imageName)}// 获取缓存图像func getFromCache(){if let returnedImage = manager.get(name: imageName){cachedImage = returnedImageinfoMessage = "Got image from cache"}else{cachedImage = nilinfoMessage = "Image not found in cache"}}
}// 缓存管理
struct CacheBootcamp: View {@StateObject var viewModel = CacheViewModel()var body: some View {NavigationView {VStack {if let image = viewModel.startingImage{Image(uiImage: image).resizable().scaledToFill().frame(width: 200, height: 200).clipped().cornerRadius(10)}Text(viewModel.infoMessage).font(.largeTitle).fontWeight(.semibold).foregroundColor(Color.purple)HStack {Button {viewModel.saveToCache()} label: {Text("Save to Cache").font(.headline).foregroundColor(.white).padding().background(Color.accentColor).cornerRadius(10)}Button {viewModel.removeFromCache()} label: {Text("Delete from Cache").font(.headline).foregroundColor(.white).padding().background(Color.red).cornerRadius(10)}}Button {viewModel.getFromCache()} label: {Text("Get from Cache").font(.headline).foregroundColor(.white).padding().background(Color.green).cornerRadius(10)}if let image = viewModel.cachedImage{Image(uiImage: image).resizable().scaledToFill().frame(width: 200, height: 200).clipped().cornerRadius(10)}Spacer()}.navigationTitle("Cache Bootcamp")}}
}

  2.2 效果图