Resizing image to fit UIImageView

I am very new to objective c and I'm just getting my bearings. I want to do something really simple but it proves to be quite a challenge:

I am trying to display an image into an UIImageView. The image I'm showing is large and I want it scaled down to fit the UIImageView. I tried setting the AspectFit View mode but the image gets displayed to the original size and is clipped by the UIImageView. My code is below:

- (void)changeImages
{
    UIImage* img11 = nil;

    img11 = [UIImage imageWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"dog" ofType:@"jpeg"]];

    u11.contentMode = UIViewContentModeScaleAspectFit;
    u11.image = img11;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    [self changeImages];
}

Can anyone shed some light on this please?

Thanks!