#import "ViewController.h"  @interface ViewController ()  @property (weak, nonatomic) IBOutlet UIImageView *backgroundView; @property (strong,nonatomic) NSArray *array;  @end  @implementation ViewController  -(NSArray *)array {  if (_array == nil) {   UIImage *image1 = [UIImage imageNamed:@"01.jpg"];   UIImage *image2 = [UIImage imageNamed:@"02.jpg"];   _array = @[image1,image2];  }  return _array; }  - (void)viewDidLoad {  [super viewDidLoad];  self.backgroundView.image = self.array[0];  // Do any additional setup after loading the view, typically from a nib. }  -(void)changeImage {  if (self.backgroundView.image == self.array[0]) {   self.backgroundView.image = self.array[1];  }else {   self.backgroundView.image = self.array[0];  } }  - (IBAction)pushClick:(id)sender {  [self changeImage];  CATransition *transtion = [[CATransition alloc] init];  transtion.type = @"push";  transtion.subtype = kCATransitionFromBottom;  transtion.startProgress = 0.5;  transtion.endProgress = 0.8;  [self.view.layer addAnimation:transtion forKey:nil]; }  /*  效果有好多種，上面代碼只貼出了其中一種，如果需要其他效果，只需要將  transtion.type = @"push";中的type改一下就行。  比如：  transtion.type = @"fade";  type的類型還有以下幾種：  fade，reveal，moveIn，cube，suckEffect，oglFlip，rippleEffect，pageCurl，pageCurl，cameraIrisHollowOpen，cameraIrisHollowClose，pageUnCurl，pageCurl，pageCurl，pageCurl   */  - (void)didReceiveMemoryWarning {  [super didReceiveMemoryWarning];  // Dispose of any resources that can be recreated. }