UI: 在导航栏显示一张图片

- (void)viewDidLoad{
[super viewDidLoad];
self.view.backgroundColor = [UIColor whiteColor];
/* Create an Image View to replace the Title View */ 
UIImageView *imageView =[[UIImageView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 100.0f, 40.0f)];
 imageView.contentMode = UIViewContentModeScaleAspectFit;
 /* Load an image. Be careful, this image will be cached */
UIImage *image = [UIImage imageNamed:@"FullSizeLogo.png"]; 
/* Set the image of the Image View */
[imageView setImage:image];
/* Set the Title View */
self.navigationItem.titleView = imageView;
}