memory leak when using CGImageCreateWithJPEGDataPr

问题:

I use Instruments(Leaks) to detect memory leaks of my app. It sometimes says there is a memory leak in one of my methods. I am not sure whether there is a leak and how to solve it.

CGImageCreateWithJPEGDataProvider method cause the memory leak mainly. Sometimes CGDataProviderCreateWithData also cause memory leak. But i don't know why.

The leak method in Class A is as follows:

- (ResultHolder *)decodeData:(UInt8 *) data withOffset:(int) offset {

    const int length = [IOUtilities byteArrayToIntWithData:data Offset:offset+18];
    UInt8 *buffer = malloc(length*sizeof(UInt8));
    memcpy(buffer, data+offset+22, length);

    // sometimes memory leak in this line
    CGDataProviderRef jpgDataProvider = CGDataProviderCreateWithData(NULL, buffer, length, freeData);

    // mainly memory leak in this line.
    CGImageRef image = CGImageCreateWithJPEGDataProvider(jpgDataProvider, NULL, true, kCGRenderingIntentSaturation);


    CGDataProviderRelease(jpgDataProvider);        
    ResultHolder *result = [[ResultHolder alloc] initWithCGImage:image];//sometimes memory leaks in this line.
    CGImageRelease(image);
    return result;
}

Also some other related methods:

// class A free buffer callback.
void freeData(void *info, const void *data, size_t size) {
    free((void *)data);
}
// class ReslutHolder init and dealloc.
- (id)initWithCGImage:(CGImageRef)image {
    if (self = [super init]) {
        CGImageRetain(image);

        //sometimes memory leak in this line.
        mBitmap = CGImageCreateCopy(image);

        mWidth = CGImageGetWidth(image);
        mHeight = CGImageGetHeight(image);
        CGImageRelease(image);
    }
    return self;
}

- (void)dealloc {
    if (mBitmap != NULL) {
        CGImageRelease(mBitmap);
        mBitmap = NULL;
    }
}

And I release mBitmap in the dealloc.

Thanks in advance.

回答1:

You can analyze the Memory Leaks in the Xcode using the analyzer as shown below

Mentioning the memory leaks shown as below would help in further solving your problem

回答2:

You should free the memory you allocated for your buffer.

free(buffer);