视觉还原

- (void) viewDidAppear:(BOOL)animated{    UIView *view=(UIView *)[[AppDelegate appDelegate].window viewWithTag:800];    [view removeFromSuperview];    UIImageView *bgImage = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0,320,480)];    bgImage.tag = 800;    [bgImage setImage:[UIImage imageNamed:@"testSubject.png"]];    [bgImage setAlpha:0.4];    [[AppDelegate appDelegate].window addSubview:bgImage];}