Денис

"Пища для ума" (с)
Синий прямоугольник, но только Xcode + Objective-C

#import <Foundation/Foundation.h>

int main(int argc, const char *argv[]) {
    const NSUInteger WIDTH = 100;
    const NSUInteger HEIGHT = 200;
    const NSUInteger COMPONENTS_PER_PIXEL = 4;
    const NSUInteger BITS_PER_COMPONENT = 8;
    const NSUInteger BUFFER_LENGTH = WIDTH * HEIGHT * COMPONENTS_PER_PIXEL;

    char *buffer = (char *) malloc(BUFFER_LENGTH);
    for (NSUInteger i = 0; i < BUFFER_LENGTH; i += 4) {
        buffer[i + 0] = 0x00;
        buffer[i + 1] = 0x00;
        buffer[i + 2] = 0xFF;
        buffer[i + 3] = 0xFF;
    }

    CGDataProviderRef dataProvider = CGDataProviderCreateWithData(NULL, buffer, BUFFER_LENGTH, NULL);
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGImageRef image = CGImageCreate(WIDTH, HEIGHT, BITS_PER_COMPONENT, BITS_PER_COMPONENT * COMPONENTS_PER_PIXEL, COMPONENTS_PER_PIXEL * WIDTH, colorSpace, kCGBitmapByteOrderDefault | kCGImageAlphaLast, dataProvider, NULL, false, kCGRenderingIntentDefault);

    NSString *filePath = @"~/test.png";
    NSURL *url = [NSURL fileURLWithPath:[filePath stringByExpandingTildeInPath]];
    CGImageDestinationRef imageDestination = CGImageDestinationCreateWithURL((__bridge CFURLRef) url, kUTTypePNG, 1, NULL);

    CGImageDestinationAddImage(imageDestination, image, NULL);

    CGImageDestinationFinalize(imageDestination);
    CGImageRelease(image);
    CGColorSpaceRelease(colorSpace);
    CGDataProviderRelease(dataProvider);
    free(buffer);

    return 0;
}