Save images in NSUserDefaults?

Is it possible to save images into NSUserDefa开发者_如何学Pythonults as an object and then retrieve for further use?

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To save an image in NSUserDefaults:

[[NSUserDefaults standardUserDefaults] setObject:UIImagePNGRepresentation(image) forKey:key];

To retrieve an image from NSUserDefaults:

NSData* imageData = [[NSUserDefaults standardUserDefaults] objectForKey:key];
UIImage* image = [UIImage imageWithData:imageData];

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ATTENTION! IF YOU'RE WORKING UNDER iOS8/XCODE6 SEE MY UPDATE BELOW

For those who still looking for answer here is code of "advisable" way to save image in NSUserDefaults. You SHOULD NOT save image data directly into NSUserDefaults!

Write data:

// Get image data. Here you can use UIImagePNGRepresentation if you need transparency
NSData *imageData = UIImageJPEGRepresentation(image, 1);

// Get image path in user's folder and store file with name image_CurrentTimestamp.jpg (see documentsPathForFileName below)
NSString *imagePath = [self documentsPathForFileName:[NSString stringWithFormat:@"image_%f.jpg", [NSDate timeIntervalSinceReferenceDate]]];

// Write image data to user's folder
[imageData writeToFile:imagePath atomically:YES];

// Store path in NSUserDefaults
[[NSUserDefaults standardUserDefaults] setObject:imagePath forKey:kPLDefaultsAvatarUrl];

// Sync user defaults
[[NSUserDefaults standardUserDefaults] synchronize];

Read data:

NSString *imagePath = [[NSUserDefaults standardUserDefaults] objectForKey:kPLDefaultsAvatarUrl];
if (imagePath) {
    self.avatarImageView.image = [UIImage imageWithData:[NSData dataWithContentsOfFile:imagePath]];
}

documentsPathForFileName:

- (NSString *)documentsPathForFileName:(NSString *)name {
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsPath = [paths objectAtIndex:0];

    return [documentsPath stringByAppendingPathComponent:name];
}

For iOS8/XCODE6 As tmr and DevC mentioned in comments below there is a problem with xcode6/ios8. The difference between xcode5 and xcode 6 installation process is that xcode6 changes apps UUID after each run in xcode (see hightlighted part in path: /var/mobile/Containers/Data/Application/B0D49CF5-8FBE-4F14-87AE-FA8C16A678B1/Documents/image.jpg).

So there are 2 workarounds:

1. Skip that problem, as once app installed on real device it's never changes UUID (in fact it does, but it is new app)
2. Save relative path to required folder (in our case to app's root)

Here is swift version of code as a bonus (with 2nd approach):

Write data:

let imageData = UIImageJPEGRepresentation(image, 1)
let relativePath = "image_\(NSDate.timeIntervalSinceReferenceDate()).jpg"
let path = self.documentsPathForFileName(relativePath)
imageData.writeToFile(path, atomically: true)
NSUserDefaults.standardUserDefaults().setObject(relativePath, forKey: "path")
NSUserDefaults.standardUserDefaults().synchronize()

Read data:

let possibleOldImagePath = NSUserDefaults.standardUserDefaults().objectForKey("path") as String?
if let oldImagePath = possibleOldImagePath {
    let oldFullPath = self.documentsPathForFileName(oldImagePath)
    let oldImageData = NSData(contentsOfFile: oldFullPath)
    // here is your saved image:
    let oldImage = UIImage(data: oldImageData)
}

documentsPathForFileName:

func documentsPathForFileName(name: String) -> String {
    let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true);
    let path = paths[0] as String;
    let fullPath = path.stringByAppendingPathComponent(name)

    return fullPath
}

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While it is possible to save a UIImage to NSUserDefaults, it is often not recommended as it is not the most efficient way to save images; a more efficient way is to save your image in the application's Documents Directory.

For the purpose of this question, I have attached the answer to your question, along with the more efficient way of saving a UIImage.

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NSUserDefaults (Not Recommended)

Saving to NSUserDefaults

This method allows you to save any UIImage to NSUserDefaults.

-(void)saveImageToUserDefaults:(UIImage *)image ofType:(NSString *)extension forKey:(NSString *)key {
    NSData * data;

    if ([[extension lowercaseString] isEqualToString:@"png"]) {
        data = UIImagePNGRepresentation(image);
    } else if ([[extension lowercaseString] isEqualToString:@"jpg"]) {
        data = UIImageJPEGRepresentation(image, 1.0);
    }

    NSUserDefaults * userDefaults = [NSUserDefaults standardUserDefaults];
    [userDefaults setObject:data forKey:key];
    [userDefaults synchronize];
}

This is how you call it:

[self saveImageToUserDefaults:image ofType:@"jpg" forKey:@"myImage"];
[[NSUserDefaults standardUserDefaults] synchronize];

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Loading From NSUserDefaults

This method allows you to load any UIImage from NSUserDefaults.

-(UIImage *)loadImageFromUserDefaultsForKey:(NSString *)key {
    NSUserDefaults * userDefaults = [NSUserDefaults standardUserDefaults];
    return [UIImage imageWithData:[userDefaults objectForKey:key]];
}

This is how you call it:

UIImage * image = [self loadImageFromUserDefaultsForKey:@"myImage"];

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A Better Alternative

Saving to Documents Directory

This method allows you to save any UIImage to the Documents Directory within the app.

-(void)saveImage:(UIImage *)image withFileName:(NSString *)imageName ofType:(NSString *)extension inDirectory:(NSString *)directoryPath {
    if ([[extension lowercaseString] isEqualToString:@"png"]) {
        [UIImagePNGRepresentation(image) writeToFile:[directoryPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.%@", imageName, @"png"]] options:NSAtomicWrite error:nil];
    } else if ([[extension lowercaseString] isEqualToString:@"jpg"] || [[extension lowercaseString] isEqualToString:@"jpeg"]) {
        [UIImageJPEGRepresentation(image, 1.0) writeToFile:[directoryPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.%@", imageName, @"jpg"]] options:NSAtomicWrite error:nil];
    } else {
        NSLog(@"Image Save Failed\nExtension: (%@) is not recognized, use (PNG/JPG)", extension);
    }
}

This is how you call it:

NSString * documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
[self saveImage:image withFileName:@"Ball" ofType:@"jpg" inDirectory:documentsDirectory];

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Loading From Documents Directory

This method allows you to load any UIImage from the application's Documents Directory.

-(UIImage *)loadImageWithFileName:(NSString *)fileName ofType:(NSString *)extension inDirectory:(NSString *)directoryPath {
    UIImage * result = [UIImage imageWithContentsOfFile:[NSString stringWithFormat:@"%@/%@.%@", directoryPath, fileName, [extension lowercaseString]]];

    return result;
}

This is how you call it:

NSString * documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
UIImage * image = [self loadImageWithFileName:@"Ball" ofType:@"jpg" inDirectory:documentsDirectory];

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A Different Alternative

Saving UIImage to Photo Library

This method allows you to save any UIImage to the device's Photo Library, and is called as follows:

UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);

Saving multiple UIImages to Photo Library

This method allows you to save multiple UIImages to the device's Photo Library.

-(void)saveImagesToPhotoAlbums:(NSArray *)images {
    for (int x = 0; x < [images count]; x++) {
        UIImage * image = [images objectAtIndex:x];

        if (image != nil) UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
    }
}

This is how you call it:

[self saveImagesToPhotoAlbums:images];

Where images is your NSArray composed of UIImages.

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For Swift 4

I almost tried everything in this question but no one is worked for me. and I found my solution. first I created an extension for UserDefaults like below, then just called get and set methods.

extension UserDefaults {
    func imageForKey(key: String) -> UIImage? {
        var image: UIImage?
        if let imageData = data(forKey: key) {
            image = NSKeyedUnarchiver.unarchiveObject(with: imageData) as? UIImage
        }
        return image
    }
    func setImage(image: UIImage?, forKey key: String) {
        var imageData: NSData?
        if let image = image {
            imageData = NSKeyedArchiver.archivedData(withRootObject: image) as NSData?
        }
        set(imageData, forKey: key)
    } 
}

to set image as background in settingsVC I used code below.

let croppedImage = cropImage(selectedImage, toRect: rect, viewWidth: self.view.bounds.size.width, viewHeight: self.view.bounds.size.width)

imageDefaults.setImage(image: croppedImage, forKey: "imageDefaults")

in mainVC :

let bgImage = imageDefaults.imageForKey(key: "imageDefaults")!

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For swift 2.2

To store:

NSUserDefaults.standardUserDefaults().setObject(UIImagePNGRepresentation(chosenImage), forKey: kKeyImage)

To retrieve:

if let imageData = NSUserDefaults.standardUserDefaults().objectForKey(kKeyImage),
            let image = UIImage(data: imageData as! NSData){
            // use your image here...
}

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Yes , technically possible as in

[[NSUserDefaults standardUserDefaults] setObject:UIImagePNGRepresentation(image) forKey:@"foo"];

But not advisable because plists are not appropriate places for large blobs of binary data especially User Prefs. It would be better to save image to user docs folder and store the reference to that object as a URL or path.

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For Swift 3 and JPG format

Register Default Image :

UserDefaults.standard.register(defaults: ["key":UIImageJPEGRepresentation(image, 100)!])

Save Image :

UserDefaults.standard.set(UIImageJPEGRepresentation(image, 100), forKey: "key")

Load Image :

let imageData = UserDefaults.standard.value(forKey: "key") as! Data
let imageFromData = UIImage(data: imageData)!

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It's technically possible, but it's not advisable. Save the image to disk instead. NSUserDefaults is meant for small settings, not big binary data files.

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From apple documentation,

The NSUserDefaults class provides convenience methods for accessing common types such as floats, doubles, integers, Booleans, and URLs. A default object must be a property list, that is, an instance of (or for collections a combination of instances of): NSData, NSString, NSNumber, NSDate, NSArray, or NSDictionary. If you want to store any other type of object, you should typically archive it to create an instance of NSData.

You can save image like this:-

[[NSUserDefaults standardUserDefaults] setObject:UIImagePNGRepresentation([UIImage imageNamed:@"yourimage.gif"])forKey:@"key_for_your_image"];

And read like this:-

 NSData* imageData = [[NSUserDefaults standardUserDefaults]objectForKey:@"key_for_your_image"];
    UIImage* image = [UIImage imageWithData:imageData];

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Save image to NSUserDefault:

NSData *imageData; 
// create NSData-object from image
imageData = UIImagePNGRepresentation([dic objectForKey:[NSString stringWithFormat:@"%d",i]]); 
// save NSData-object to UserDefaults
[[NSUserDefaults standardUserDefaults] setObject:imageData forKey:[NSString stringWithFormat:@"%d",i]];

Load Image from NSUserDefault:

NSData *imageData;
// Load NSData-object from NSUserDefault
imageData = [[NSUserDefaults standardUserDefaults] valueForKey:[NSString stringWithFormat:@"%d",i]];
// get Image from NSData
[image setObject:[UIImage imageWithData:imageData] forKey:[NSString stringWithFormat:@"%d",i]];

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Yes, you can use. But since it is for storage of preferences, you can better save images to document folder.

And you can have the path in the NSUserDefaults, if required.

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Since this question has a high google search index - here's @NikitaTook's answer in today's day and age i.e. Swift 3 and 4 (with exception handling).

Note: This class is solely written to read and write images of JPG format to the filesystem. The Userdefaults stuff should be handled outside of it.

writeFile takes in the file name of your jpg image (with .jpg extension) and the UIImage itself and returns true if it is able to save or else returns false if it is unable to write the image, at which point you can store the image in Userdefaults which would be your backup plan or simply retry one more time. The readFile function takes in the image file name and returns a UIImage, if the image name passed to this function is found then it returns that image else it just returns a default placeholder image from the app's asset folder (this way you can avoid nasty crashes or other weird behaviors).

import Foundation
import UIKit

class ReadWriteFileFS{

    func writeFile(_ image: UIImage, _ imgName: String) -> Bool{
        let imageData = UIImageJPEGRepresentation(image, 1)
        let relativePath = imgName
        let path = self.documentsPathForFileName(name: relativePath)

        do {
            try imageData?.write(to: path, options: .atomic)
        } catch {
            return false
        }
        return true
    }

    func readFile(_ name: String) -> UIImage{
        let fullPath = self.documentsPathForFileName(name: name)
        var image = UIImage()

        if FileManager.default.fileExists(atPath: fullPath.path){
            image = UIImage(contentsOfFile: fullPath.path)!
        }else{
            image = UIImage(named: "user")!  //a default place holder image from apps asset folder
        }
        return image
    }
}

extension ReadWriteFileFS{
    func documentsPathForFileName(name: String) -> URL {
        let paths = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
        let path = paths[0]
        let fullPath = path.appendingPathComponent(name)
        return fullPath
    }
}

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Swift 4.x
Xcode 11.x

func saveImageInUserDefault(img:UIImage, key:String) {
    UserDefaults.standard.set(img.pngData(), forKey: key)
}

func getImageFromUserDefault(key:String) -> UIImage? {
    let imageData = UserDefaults.standard.object(forKey: key) as? Data
    var image: UIImage? = nil
    if let imageData = imageData {
        image = UIImage(data: imageData)
    }
    return image
}