iOS UIImageView图片自动拉伸功能

- (void)viewDidLoad {   [super viewDidLoad];      UIImage *smallImage = [UIImage imageNamed:@"hc_03.png"];    UIImageView *imageView = [[UIImageView alloc] initWithImage:smallImage];   [imageView setFrame:CGRectMake(0, 20, 320, 44)];   imageView.contentMode = UIViewContentModeScaleToFill;   [self.view addSubview:imageView];    [imageView release];      }