CGFloat width = any value; 　CGFloat height = any value; CGDataProviderRef dataProviderRef = dataProviderRef = CGDataProviderCreateWithData(NULL, data, width * height * 2, nil); CGBitmapInfo bitmapInfo = kCGBitmapByteOrderMask | kCGImageAlphaNoneSkipLast; CGImageRef imageResult = CGImageCreate(width, height, 8, 16, width * 2, CGColorSpaceCreateDeviceGray(), bitmapInfo, dataProviderRef, NULL, 0, kCGRenderingIntentDefault); imageResult is nil. Please tell me an alternative method.