- (UIImage *) imageBlackToTransparent { // 分配内存 const int imageWidth = self.size.width; const int imageHeight = self.size.height; size_t bytesPerRow = imageWidth * 4; uint32_t *rgbImageBuf = (uint32_t *)malloc(bytesPerRow * imageHeight); // 创建context CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); CGContextRef context = CGBitmapContextCreate(rgbImageBuf, imageWidth, imageHeight, 8, bytesPerRow, colorSpace,kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast); CGContextDrawImage(context, CGRectMake(0, 0, imageWidth, imageHeight), self.CGImage); // 遍历像素 int pixelNum = imageWidth * imageHeight; uint32_t *pCurPtr = rgbImageBuf; for (int i = 0; i < pixelNum; i++, pCurPtr++){ int w = imageWidth - (i % imageWidth); bool shouldFade = (w <= 30.0); if (shouldFade) { uint8_t *ptr = (uint8_t *)pCurPtr; ptr[0] = ((float)(w)/30.0)*255; } } // 将内存转成image CGDataProviderRef dataProvider = CGDataProviderCreateWithData(NULL, rgbImageBuf, bytesPerRow * imageHeight,ProviderReleaseData); CGImageRef imageRef = CGImageCreate(imageWidth, imageHeight, 8, 32, bytesPerRow, colorSpace,kCGImageAlphaLast | kCGBitmapByteOrder32Little, dataProvider,NULL, true, kCGRenderingIntentDefault); CGDataProviderRelease(dataProvider); UIImage* resultUIImage = [UIImage imageWithCGImage:imageRef]; // 释放 CGImageRelease(imageRef); CGContextRelease(context); CGColorSpaceRelease(colorSpace); // free(rgbImageBuf) 创建dataProvider时已提供释放函数，这里不用free return resultUIImage; } /** 颜色变化 */ void ProviderReleaseData (void *info, const void *data, size_t size){ free((void *)data); }