Memory leak after call CGContextDrawImage - objective-c

Question

I've read all CGContextDrawImage memory peak answers, I tried but none of the solutions work yet.
Here is my code, after call CGContextDrawImage, memory increase 10-40MB. I'm using this code to generate a video from images, if I have 200 images, the app crash.
Loop through images:
for(UIImage * img in imageArray)
{
buffer = [self pixelBufferFromCGImage:[img CGImage] ImageSize:img.size];
BOOL append_ok = NO;
int j = 0;
while (!append_ok) {
if (adaptor.assetWriterInput.readyForMoreMediaData) {
//print out status:
NSLog(#"Processing video frame (%d,%lu)",frameCount,(unsigned long)[imageArray count]);
CMTime frameTime = CMTimeMake(frameCount*frameDuration,(int32_t) fps);
append_ok = [adaptor appendPixelBuffer:buffer withPresentationTime:frameTime];
if(!append_ok){
NSError *error = videoWriter.error;
if(error!=nil) {
NSLog(#"Unresolved error %#,%#.", error, [error userInfo]);
}
}
}
else {
printf("adaptor not ready %d, %d\n", frameCount, j);
[NSThread sleepForTimeInterval:0.1];
}
}
if (!append_ok) {
printf("error appending image %d times %d\n, with error.", frameCount, j);
}
frameCount++;
}
Here is pixelBufferFromCGImage function
- (CVPixelBufferRef) pixelBufferFromCGImage: (CGImageRef) image ImageSize:(CGSize)size {
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], kCVPixelBufferCGImageCompatibilityKey,
[NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey,
nil];
CVPixelBufferRef pxbuffer = NULL;
CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault,
size.width,
size.height,
kCVPixelFormatType_32ARGB,
(__bridge CFDictionaryRef) options,
&pxbuffer);
if (status != kCVReturnSuccess){
NSLog(#"Failed to create pixel buffer");
}
CVPixelBufferLockBaseAddress(pxbuffer, 0);
void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);
CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(pxdata, size.width,
size.height, 8, 4*size.width, rgbColorSpace,
kCGImageAlphaPremultipliedFirst);
//kCGImageAlphaNoneSkipFirst);
CGContextConcatCTM(context, CGAffineTransformMakeRotation(0));
CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image),
CGImageGetHeight(image)), image);
CGColorSpaceRelease(rgbColorSpace);
CGContextRelease(context);
CVPixelBufferUnlockBaseAddress(pxbuffer, 0);
return pxbuffer;
}