gistfile1.m

#import <UIKit/UIKit.h>
#import <ImageIO/ImageIO.h>
#import <MobileCoreServices/MobileCoreServices.h>

- (void)exportAnimatedGif
{
    UIImage *shacho = [UIImage imageNamed:@"shacho.png"];
    UIImage *bucho = [UIImage imageNamed:@"bucho.jpeg"];
    
    NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"animated.gif"];
    CGImageDestinationRef destination = CGImageDestinationCreateWithURL((CFURLRef)[NSURL fileURLWithPath:path],
                                                                        kUTTypeGIF,
                                                                        2,
                                                                        NULL);
    
    NSDictionary *frameProperties = [NSDictionary dictionaryWithObject:[NSDictionary dictionaryWithObject:[NSNumber numberWithInt:2] forKey:(NSString *)kCGImagePropertyGIFDelayTime]
                                                                                                   forKey:(NSString *)kCGImagePropertyGIFDictionary];
    NSDictionary *gifProperties = [NSDictionary dictionaryWithObject:[NSDictionary dictionaryWithObject:[NSNumber numberWithInt:0] forKey:(NSString *)kCGImagePropertyGIFLoopCount]
                                                              forKey:(NSString *)kCGImagePropertyGIFDictionary];
    
    CGImageDestinationAddImage(destination, shacho.CGImage, (CFDictionaryRef)frameProperties);
    CGImageDestinationAddImage(destination, bucho.CGImage, (CFDictionaryRef)frameProperties);
    CGImageDestinationSetProperties(destination, (CFDictionaryRef)gifProperties);
    CGImageDestinationFinalize(destination);
    CFRelease(destination);
    NSLog(@"animated GIF file created at %@", path);
}