Yes, I fix this problem, and UIImage is correct, but actually I still get the nil data to create MTLTexture. But When I load a png file, everything is ok This is my test code: self.device = MTLCreateSystemDefaultDevice();       // My Text Image   CIFilter<CITextImageGenerator> * filter = [CIFilter textImageGeneratorFilter];    filter.text = @"This is a test text";    filter.fontName = @"HoeflerText-Regular";    filter.fontSize = 12;    filter.scaleFactor = 1.0;    CIImage *image = filter.outputImage;    CIContext *cicontext = [CIContext contextWithOptions:nil];    CGImageRef resultRef = [cicontext createCGImage:image fromRect:image.extent];    UIImage *resultImage = [UIImage imageWithCGImage:resultRef];   // PNG Image //  UIImage *resultImage = [UIImage imageNamed:@"nx"]; //  CGImageRef resultRef = resultImage.CGImage;         CFDataRef data = CGDataProviderCopyData(CGImageGetDataProvider(resultRef));    const unsigned char * buffer = CFDataGetBytePtr(data);       CGFloat width = CGImageGetWidth(resultRef), height = CGImageGetHeight(resultRef);   NSInteger bytesPerPixel = 4, bytesPerRow = bytesPerPixel * width, bitsPerComponent = 8;   CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();   void *rawData = calloc(height * width * bytesPerPixel, sizeof(uint8_t));   if (rawData == nil) {     CGColorSpaceRelease(colorSpace);     colorSpace = NULL;   }   CGContextRef context = CGBitmapContextCreate(rawData, width, height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast|kCGImageByteOrder32Big);   CGColorSpaceRelease(colorSpace);   colorSpace = NULL;   if (context == nil) {     free(rawData);   }   CGContextTranslateCTM(context, 0, height);   CGContextScaleCTM(context, 1, -1);   CGContextDrawImage(context, CGRectMake(0, 0, width, height), resultRef);       MTLTextureDescriptor *textureDescriptor = [MTLTextureDescriptor texture2DDescriptorWithPixelFormat:MTLPixelFormatRGBA8Unorm width:width height:height mipmapped:NO];   id<MTLTexture> texture = [self.device newTextureWithDescriptor:textureDescriptor];   if (!texture) {     free(rawData);     CGContextRelease(context);   }   MTLRegion region = MTLRegionMake3D(0, 0, 0, width, height, 1);   [texture replaceRegion:region mipmapLevel:0 withBytes:rawData bytesPerRow:bytesPerRow];   free(rawData);   CGContextRelease(context);   _fontTexture = texture; Thank you very much!

This is my test image named nx