- (void)viewDidLoad{    [super viewDidLoad];    // Do any additional setup after loading the view.        //初始化背景图    [self initBackgroundView];}#pragma -mark -functions-(void)initBackgroundView{    self.title=@"翻书效果的实现";    self.view.backgroundColor=[UIColor redColor];        //upButton    UIButton *upButton = [UIButton buttonWithType:UIButtonTypeCustom];    upButton.frame = CGRectMake(20, 420, 50, 26);    upButton.backgroundColor=[UIColor blueColor];    [upButton setTitle:@"up" forState:UIControlStateNormal];    [upButton addTarget:self action:@selector(doClickUpButton) forControlEvents:UIControlEventTouchUpInside];    [self.view addSubview:upButton];        //downButton    UIButton *downButton = [UIButton buttonWithType:UIButtonTypeCustom];    downButton.frame = CGRectMake(250, 420, 50, 26);    downButton.backgroundColor=[UIColor blueColor];    [downButton setTitle:@"down" forState:UIControlStateNormal];    [downButton addTarget:self action:@selector(doClickDownButton) forControlEvents:UIControlEventTouchUpInside];    [self.view addSubview:downButton];}#pragma -mark -doClickAction-(void)doClickUpButton{    [UIView beginAnimations:nil context:nil];    [UIView setAnimationDuration:0.7];    [UIView setAnimationTransition:UIViewAnimationTransitionCurlDown forView:self.view cache:YES];    [UIView commitAnimations];}-(void)doClickDownButton{    [UIView beginAnimations:nil context:nil];    [UIView setAnimationDuration:0.7];    [UIView setAnimationTransition:UIViewAnimationTransitionCurlUp forView:self.view cache:YES];    [UIView commitAnimations];}