如何使用 writeToFile 将图像保存在文档目录中？

Question

// directoryPath is a URL from another VC
@IBAction func saveButtonTapped(sender: AnyObject) {
            let directoryPath           =  NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0] as NSURL
            let urlString : NSURL       = directoryPath.URLByAppendingPathComponent("Image1.png")
            print("Image path : \(urlString)")
            if !NSFileManager.defaultManager().fileExistsAtPath(directoryPath.absoluteString) {
                UIImageJPEGRepresentation(self.image, 1.0)!.writeToFile(urlString.absoluteString, atomically: true)
                displayImageAdded.text  = "Image Added Successfully"
            } else {
                displayImageAdded.text  = "Image Not Added"
                print("image \(image))")
            }
        }

我没有收到任何错误，但图像没有保存在文档中。

Answer 1

问题在于您正在检查文件夹是否不存在，但您应该检查文件是否存在。 您代码中的另一个问题是您需要使用 url.path 而不是 url.absoluteString。 您还使用“png”文件扩展名保存 jpeg 图像。 你应该使用“jpg”。

编辑/更新：

Swift 4.2 或更高版本

// get the documents directory url
let documentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
// choose a name for your image
let fileName = "image.jpg"
// create the destination file url to save your image
let fileURL = documentsDirectory.appendingPathComponent(fileName)
// get your UIImage jpeg data representation and check if the destination file url already exists
if let data = image.jpegData(compressionQuality:  1.0),
  !FileManager.default.fileExists(atPath: fileURL.path) {
    do {
        // writes the image data to disk
        try data.write(to: fileURL)
        print("file saved")
    } catch {
        print("error saving file:", error)
    }
}

Answer 2

这是我对Swift 3 的回答，结合了上面的 2 个回答：

let documentsDirectoryURL = try! FileManager().url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: true)
// create a name for your image
let fileURL = documentsDirectoryURL.appendingPathComponent("Savedframe.png")


if !FileManager.default.fileExists(atPath: fileURL.path) {
    do {
        try UIImagePNGRepresentation(imageView.image!)!.write(to: fileURL)
            print("Image Added Successfully")
        } catch {
            print(error)
        }
    } else {
        print("Image Not Added")
}

Answer 3

swift 4.2 中的扩展方法

import Foundation
import UIKit

extension UIImage {

    func saveToDocuments(filename:String) {
        let documentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
        let fileURL = documentsDirectory.appendingPathComponent(filename)
        if let data = self.jpegData(compressionQuality: 1.0) {
            do {
                try data.write(to: fileURL)
            } catch {
                print("error saving file to documents:", error)
            }
        }
    }

}

Answer 4

@IBAction func saveButtonTapped(sender: AnyObject) {
let directoryPath           =  try! NSFileManager().URLForDirectory(.DocumentDirectory, inDomain: .UserDomainMask, appropriateForURL: nil, create: true)    
let urlString : NSURL       = directoryPath.URLByAppendingPathComponent("Image1.png")
    print("Image path : \(urlString)")
    if !NSFileManager.defaultManager().fileExistsAtPath(urlString.path!) {
        UIImageJPEGRepresentation(self.image, 1.0)!.writeToFile(urlString.path! , atomically: true)
        displayImageAdded.text  = "Image Added Successfully"
    } else {
        displayImageAdded.text  = "Image Not Added"
        print("image \(image))")
    }
}

Answer 5

将图像放入 NSData 对象中； 用这个类写入文件是轻而易举的，它会使文件更小。

顺便说一下，我推荐 NSPurgeableData。 保存图像后，您可以将对象标记为可清除，这将保持内存消耗。 这可能是您的应用程序的问题，但可能是您排挤的另一个问题。

Answer 6

在 Swift 4.2 和 Xcode 10.1 中

func saveImageInDocsDir() {

    let image: UIImage? = yourImage//Here set your image
    if !(image == nil) {
        // get the documents directory url
        let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
        let documentsDirectory = paths[0] // Get documents folder
        let dataPath = URL(fileURLWithPath: documentsDirectory).appendingPathComponent("ImagesFolder").absoluteString //Set folder name
        print(dataPath)
        //Check is folder available or not, if not create 
        if !FileManager.default.fileExists(atPath: dataPath) {
            try? FileManager.default.createDirectory(atPath: dataPath, withIntermediateDirectories: true, attributes: nil) //Create folder if not
        }

        // create the destination file url to save your image
        let fileURL = URL(fileURLWithPath:dataPath).appendingPathComponent("imageName.jpg")//Your image name
        print(fileURL)
        // get your UIImage jpeg data representation
        let data = UIImageJPEGRepresentation(image!, 1.0)//Set image quality here
        do {
            // writes the image data to disk
            try data?.write(to: fileURL, options: .atomic)
        } catch {
            print("error:", error)
        }
    }
}

Answer 7

虽然答案是正确的，但我想为此目的共享实用程序功能。 您可以使用以下两种方法将图像保存在文档目录中，然后从文档目录中加载图像。 在这里您可以找到详细文章。

public static func saveImageInDocumentDirectory(image: UIImage, fileName: String) -> URL? {

        let documentsUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!;
        let fileURL = documentsUrl.appendingPathComponent(fileName)
        if let imageData = UIImagePNGRepresentation(image) {
            try? imageData.write(to: fileURL, options: .atomic)
            return fileURL
        }
        return nil
    }

public static func loadImageFromDocumentDirectory(fileName: String) -> UIImage? {

        let documentsUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!;
        let fileURL = documentsUrl.appendingPathComponent(fileName)
        do {
            let imageData = try Data(contentsOf: fileURL)
            return UIImage(data: imageData)
        } catch {}
        return nil
    }

Answer 8

Swift 5.x 的答案

func saveImageToDocumentsDirectory() {
        let directoryPath =  try! FileManager().url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: true)
        let urlString : NSURL = directoryPath.appendingPathComponent("Image1.png") as NSURL
            print("Image path : \(urlString)")
        if !FileManager.default.fileExists(atPath: urlString.path!) {
            do {
                try self.image.jpegData(compressionQuality: 1.0)!.write(to: urlString as URL)
                print ("Image Added Successfully")
            } catch {
                print ("Image Not added")
            }
        }
    }

注意：图像 = 您声明的图像。