method to create UIImage from CIImage and avoid memory leak of iOS9.0 described there: https://forums.developer.apple.com/thread/17142

UIImage-CIImageUtils.m

// initial swift code taken from https://forums.developer.apple.com/thread/17142
// or you can kill current EAGLContext and create new one before CIContext creation
// but it is more expensive
// [EAGLContext setCurrentContext:nil];

#import "UIImage-CIImageUtils.h"

@implementation UIImage (CIImageUtils)

static const size_t kComponentsPerPixel = 4;
static const size_t kBitsPerComponent = sizeof(unsigned char) * 8;

static void releasePixels(void *info, const void *data, size_t size)
{
    free((void*)data);
}

+ (UIImage *) imageFromCIImage:(CIImage *)img scale:(CGFloat)scale orientation:(UIImageOrientation)orientation
{
    int width = (int)img.extent.size.width;
    int height = (int)img.extent.size.height;
    
    long memsize = sizeof(unsigned char) * width * height * kComponentsPerPixel;
    
    unsigned char *rawData = malloc(memsize);
    
    CIContext *context = [CIContext contextWithOptions:@{kCIContextUseSoftwareRenderer: @NO}];
    
    CGColorSpaceRef rgb = CGColorSpaceCreateDeviceRGB();
    
    [context render:img toBitmap:rawData rowBytes:width*kComponentsPerPixel bounds:img.extent format:kCIFormatRGBA8 colorSpace:rgb];
    
    CGDataProviderRef provider = CGDataProviderCreateWithData(nil, rawData, memsize, releasePixels);
    
    CGImageRef imageFromContext = CGImageCreate(width,
                                                height,
                                                kBitsPerComponent,
                                                kBitsPerComponent * kComponentsPerPixel,
                                                width*kComponentsPerPixel,
                                                rgb,
                                                kCGBitmapByteOrderDefault | kCGImageAlphaLast,
                                                provider,
                                                NULL,
                                                false,
                                                kCGRenderingIntentDefault);

    UIImage *outImage = [UIImage imageWithCGImage:imageFromContext scale:scale orientation:orientation];
    
    CGImageRelease(imageFromContext);
    CGDataProviderRelease(provider);
    CGColorSpaceRelease(rgb);
    
    return outImage;
}

@end