实现多个UIView之间切换的动画效果

@interface RootViewController (){
UIView *view1;
UIView *view2;
int    flag;
}

@end

@implementation RootViewController

- (void)viewDidLoad
{
[super viewDidLoad];
flag = 1;

UIButton *button = [[UIButton alloc]initWithFrame:CGRectMake(130, 65, 50, 35)];
[button setTitle:@"点击" forState:UIControlStateNormal];
[button setTitleColor:[UIColor greenColor] forState:UIControlStateNormal];
[button addTarget:self action:@selector(click) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:button];

view1 = [[UIView alloc]initWithFrame:CGRectMake(0, 100, 320, 480)];
view1.backgroundColor = [UIColor grayColor];

view2 = [[UIView alloc]initWithFrame:CGRectMake(0, 100, 320, 480)];
view2.backgroundColor = [UIColor orangeColor];
}

- (void)click{

[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:0.6f];
[UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:self.view cache:NO];

if (flag == 1) {

[self.view addSubview:view1];
flag = 2;

}else if(flag == 2){

[self.view addSubview:view2];
flag = 1;
}
[UIView commitAnimations];
}