how to use writeToFile to save image in document directory?

问题

// 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))")
            }
        }

I am not getting any error but the Image is not getting saved in the document.

回答1:

The problem there is that you are checking if the folder not exists but you should check if the file exists. Another issue in your code is that you need to use url.path instead of url.absoluteString. You are also saving a jpeg image using a "png" file extension. You should use "jpg".

edit/update:

Swift 4.2 or later

// 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)
    }
}

回答2:

This is my answer for Swift 3, combining the 2 answers above:

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")
}

回答3:

An extension method in swift 4.2

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)
            }
        }
    }

}

回答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))")
    }
}

回答5:

Put the image in an NSData object; writing to a file with this class is a breeze, and it'll make the file size smaller.

By the way, I recommend NSPurgeableData. After saving the image, you can mark the object as purgeable, which will keep memory consumption. That may be a problem with your app, but might be with another you're crowding out.

回答6:

In Swift 4.2 and Xcode 10.1

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)
        }
    }
}

来源：https://stackoverflow.com/questions/32836862/how-to-use-writetofile-to-save-image-in-document-directory

标签

ios

image

swift

writetofile