複数画像からGIFをつくる

generator.m

// フレームワークを2つインポート
// #import <ImageIO/ImageIO.h> -> ImageIO.framework
// #import <MobileCoreServices/MobileCoreServices.h> -> MobileCoreService.framework

+ (NSData *) generateGifDataWithImages:(NSArray *)images
{
    
    // 何秒間隔で画像を切り替えるか
    NSDictionary *frameProperties =
        @{ (NSString *)kCGImagePropertyGIFDictionary: @{ (NSString *)kCGImagePropertyGIFDelayTime : @(1) } };
    // ループのカウント(0で無限ループ)
    NSDictionary *gifProperties =
        @{ (NSString *)kCGImagePropertyGIFDictionary : @{ (NSString *)kCGImagePropertyGIFLoopCount : @0 } };
    
    long frameCount = [images count];
    CFMutableDataRef gifData = CFDataCreateMutable(kCFAllocatorDefault, 0);
    
    CGImageDestinationRef destination = CGImageDestinationCreateWithData(gifData, kUTTypeGIF, frameCount, NULL);
    
    // 渡ってきたimage分まわす
    UIImage *image;
    for (image in images) {
        CGImageDestinationAddImage(destination, image.CGImage, (__bridge CFDictionaryRef)frameProperties);
    }
    CGImageDestinationSetProperties(destination, (__bridge CFDictionaryRef)gifProperties);
    CGImageDestinationFinalize(destination);
    
    // nsdataに変換
    NSData *result = [NSData dataWithData:( NSData *)CFBridgingRelease(gifData)];
    
    // 解放処理
    CFRelease(destination);
    
    return result;
}