IOS-试图旋转效果的实现

.h

#import <UIKit/UIKit.h>@interface ZSViewController : UIViewController{    float screenWidth;    float screenHeight;}-(UIColor*)createColor:(float)r :(float)g :(float)b;@end

.m

#import "ZSViewController.h"@interface ZSViewController ()@end@implementation ZSViewController- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];    if (self) {        // Custom initialization        self.view.backgroundColor = [UIColor colorWithRed:100.0/255.0 green:200.0/255.0 blue:200.0/255.0 alpha:0.8];    }    return self;}-(UIColor*)createColor:(float)r :(float)g :(float)b{    UIColor *color = [UIColor colorWithRed:r/255.0 green:g/255.0 blue:b/255.0 alpha:0.8];    return color;}- (void)viewDidLoad{    [super viewDidLoad];    //-------------0.init    screenWidth = self.view.center.x*2;    screenHeight = self.view.center.y*2;        //-------------1.add a new view    UIView *picSwitchView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, screenWidth, screenHeight)];    picSwitchView.backgroundColor = [self createColor:100.0 :200.0 :200.0];    picSwitchView.tag = 1000;    [self.view addSubview:picSwitchView];        //-------------2.add image view    UIImageView *imageView1 = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"picture1.jpg"]];    [imageView1 setFrame:CGRectMake(0,0, screenWidth, screenHeight)];    imageView1.tag = 1001;    imageView1.backgroundColor =  [self createColor:255.0 :0 :0];    [picSwitchView addSubview:imageView1];        UIImageView *imageView2 = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"picture2.jpg"]];    [imageView2 setFrame:CGRectMake(0,0, screenWidth, screenHeight)];    imageView2.tag = 1002;    imageView2.backgroundColor = [self createColor:0.0 :255.0 :0.0];    [picSwitchView addSubview:imageView2];        //-------------3.add btn to control fanzhuan    UIButton *btnControl = [UIButton buttonWithType:UIButtonTypeSystem];    [btnControl setFrame:CGRectMake(screenWidth/2, screenHeight-30, 40, 20)];    [btnControl setTitle:@"fanzhuan" forState:UIControlStateNormal];    [btnControl addTarget:self action:@selector(fanzhuan) forControlEvents:UIControlEventTouchUpInside];    [picSwitchView addSubview:btnControl];    }-(void)fanzhuan{    NSLog(@"btn clicked!");        //1.animation operator    CGContextRef theContext = UIGraphicsGetCurrentContext();    [UIView beginAnimations:nil context:theContext];    [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];    [UIView setAnimationDuration:1.0];        //2.add anination to a view    UIView   *thePicSwitchView  = [self.view viewWithTag:1000];    [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:thePicSwitchView cache:YES];        NSInteger purple = [[thePicSwitchView subviews] indexOfObject:[thePicSwitchView viewWithTag:1002]];    NSInteger maron = [[thePicSwitchView subviews] indexOfObject:[thePicSwitchView viewWithTag:1001]];        NSLog(@"tag 1002 is :%d,tag 1001 is :%d",(int)purple,(int)maron);    [thePicSwitchView exchangeSubviewAtIndex:maron withSubviewAtIndex:purple];        [UIView setAnimationDelegate:self];    [UIView setAnimationDidStopSelector:@selector(animationFinished)];    [UIView commitAnimations];}-(void)animationFinished{    NSLog(@"animation finished!");}- (void)didReceiveMemoryWarning{    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}/*#pragma mark - Navigation// In a storyboard-based application, you will often want to do a little preparation before navigation- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{    // Get the new view controller using [segue destinationViewController].    // Pass the selected object to the new view controller.}*/@end