新建一个view-based模板工程，在ViewController文件中添加下面的代码，即可实现翻转效果；

- (void)viewDidLoad {

[super viewDidLoad];

//需要翻转的视图

UIView *parentView = [[UIView alloc] initWithFrame:CGRectMake(0, 150, 320, 200)];

parentView.backgroundColor = [UIColor yellowColor];

parentView.tag = 1000;

[self.view addSubview:parentView];

}

//需要在h头文件声明下面的动作响应函数

//在xib文件中添加一个button，其响应函数为下面的函数

//运行程序后，点击button就看到翻转效果

-(IBAction)ActionFanzhuan{

//获取当前画图的设备上下文

CGContextRef context = UIGraphicsGetCurrentContext();

//开始准备动画

[UIView beginAnimations:nil context:context];

//设置动画曲线，翻译不准，见苹果官方文档

[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];

//设置动画持续时间

[UIView setAnimationDuration:1.0];

//因为没给viewController类添加成员变量，所以用下面方法得到viewDidLoad添加的子视图

UIView *parentView = [self.view viewWithTag:1000];

//设置动画效果

[UIView setAnimationTransition: UIViewAnimationTransitionCurlDown forView:parentView cache:YES];  //从上向下

// [UIView setAnimationTransition: UIViewAnimationTransitionCurlUp forView:parentView cache:YES];   //从下向上

// [UIView setAnimationTransition: UIViewAnimationTransitionFlipFromLeft forView:parentView cache:YES];  //从左向右

// [UIView setAnimationTransition: UIViewAnimationTransitionFlipFromRight forView:parentView cache:YES];//从右向左

//设置动画委托

[UIView setAnimationDelegate:self];

//当动画执行结束，执行animationFinished方法

[UIView setAnimationDidStopSelector:@selector(animationFinished:)];

//提交动画

[UIView commitAnimations];

}

//动画效果执行完毕

- (void) animationFinished: (id) sender{

NSLog(@"animationFinished !");

}

运行程序，点击按钮，就能看到动画效果了

下面我自己在parentView上添加了两个子视图实现动画

- (void)viewDidLoad {

[super viewDidLoad];

UIView *parentView = [[UIView alloc] initWithFrame:CGRectMake(0, 150, 320, 200)];

parentView.backgroundColor = [UIColor yellowColor];

parentView.tag = 1000;

UIImageView *image1 = [[UIImageView alloc] initWithFrame:CGRectMake(50, 50, 100, 100)];

image1.backgroundColor = [UIColor redColor];

image1.tag = 1001;

UIImageView *image2 = [[UIImageView alloc] initWithFrame:CGRectMake(50, 50, 100, 100)];

image2.backgroundColor = [UIColor blueColor];

image2.tag = 1002;

[parentView addSubview:image1];

[parentView addSubview:image2];

[self.view addSubview:parentView];

}

-(IBAction)ActionFanzhuan{

CGContextRef context = UIGraphicsGetCurrentContext();

[UIView beginAnimations:nil context:context];

[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];

[UIView setAnimationDuration:1.0];

UIView *parentView = [self.view viewWithTag:1000];

[UIView setAnimationTransition: UIViewAnimationTransitionCurlDown forView:parentView cache:YES];

// [UIView setAnimationTransition: UIViewAnimationTransitionCurlUp forView:parentView cache:YES];

// [UIView setAnimationTransition: UIViewAnimationTransitionFlipFromLeft forView:parentView cache:YES];

// [UIView setAnimationTransition: UIViewAnimationTransitionFlipFromRight forView:parentView cache:YES];

NSInteger purple = [[parentView subviews] indexOfObject:[parentView viewWithTag:1002]];

NSInteger maroon = [[parentView subviews] indexOfObject:[parentView viewWithTag:1001]];

[parentView exchangeSubviewAtIndex:purple withSubviewAtIndex:maroon];

[UIView setAnimationDelegate:self];

[UIView setAnimationDidStopSelector:@selector(animationFinished:)];

[UIView commitAnimations];

}

- (void) animationFinished: (id) sender{

NSLog(@"animationFinished !");

}

另外：之前在viewDidLoad里面写实现动画的代码，但一致未实现动画效果，原来在viewDidLoad里面执行

CGContextRef context = UIGraphicsGetCurrentContext();

后context的指针为0