Storing image in plist

Question

How can we store images in plist file. Where is this plist file stored? Can anyone give me an example? Answers will be greatly appreciated!

Answer 1

The UIImage doesn't implement the NSCoder protocol directly that is necessary for storage in plists.

But, it is fairly easy to add like below.

UIImage+NSCoder.h

#import <Foundation/Foundation.h>

@interface UIImage (MyExtensions)
- (void)encodeWithCoder:(NSCoder *)encoder;
- (id)initWithCoder:(NSCoder *)decoder;
@end

UIImage+NSCoder.m

#import "UIImage+NSCoder.h"

@implementation UIImage (MyExtensions)

- (void)encodeWithCoder:(NSCoder *)encoder
{
  [encoder encodeDataObject:UIImagePNGRepresentation(self)];
}

- (id)initWithCoder:(NSCoder *)decoder
{
  return [self initWithData:[decoder decodeDataObject]];
}

@end

When this has been added you will be able to store UIImages in plist with ie

// Get a full path to a plist within the Documents folder for the app
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
                                                     NSUserDomainMask,
                                                     YES);
NSString *path = [NSString stringWithFormat:@"%@/my.plist",
                                              [paths objectAtIndex:0]];

// Place an image in a dictionary that will be stored as a plist
[dictionary setObject:image forKey:@"image"];

// Write the dictionary to the filesystem as a plist
[NSKeyedArchiver archiveRootObject:dictionary toFile:path];

Note: I do not recommend doing this, unless you really want to, ie for really small images.

Answer 2

Always store the image path in the .plist, never the actual image. If you do, you'll take a performance hit. You want to load images as you need them, not all at once.