IOS開発(90)のアニメーションビューの回転

- (void)viewDidLoad
{
    [super viewDidLoad];
    UIImage *xcodeImage = [UIImage imageNamed:@"Xcode.png"];
    self.xcodeImageView = [[UIImageView alloc] initWithImage:xcodeImage];
    //     Frame
    [self.xcodeImageView setFrame:CGRectMake(0.0f,0.0f, 100.0f, 100.0f)];
    self.view.backgroundColor = [UIColor whiteColor];
    [self.view addSubview:self.xcodeImageView];
}

- (void) viewDidAppear:(BOOL)paramAnimated{ [super viewDidAppear:paramAnimated];
    self.xcodeImageView.center = self.view.center;
    /* Begin the animation */
    [UIView beginAnimations:@"clockwiseAnimation" context:NULL];
    /* Make the animation 5 seconds long */
    [UIView setAnimationDuration:5.0f];
    [UIView setAnimationDelegate:self];
    //        clockwiseRotationStopped  
    [UIView setAnimationDidStopSelector:@selector(clockwiseRotationStopped:finished:context:)];
    //     90 
    self.xcodeImageView.transform = CGAffineTransformMakeRotation((90.0f * M_PI) / 180.0f);
    /* Commit the animation */
    [UIView commitAnimations];
}

- (void)clockwiseRotationStopped:(NSString *)paramAnimationID finished:(NSNumber *)paramFinished
                         context:(void *)paramContext{
    [UIView beginAnimations:@"counterclockwiseAnimation"context:NULL];
    /* 5 seconds long */
    [UIView setAnimationDuration:5.0f];
    /*        */
    self.xcodeImageView.transform = CGAffineTransformIdentity;
    [UIView commitAnimations];
}